2005-09-01

Blood groups and true parents

You can't respond anonymously any more. Just make up an identity. Sorry, but the spam got out of control.

Blood type calculator: enter blood types for both parents and find out possible blood types for a child, or blood types for one parent and one child and find out possible blood types for the other parent. Please use this first!

I got a letter two years ago from someone who very much wanted help disentangling her family history. She wrote to me:

I have just found my deceased father's blood group, and it has got me worried. I am AB, my brother is O, my sister is O, and so was my father. My mother was type AB, I think. So the burning question is, Is my father really my father?

I replied:

As you may know, you have two copies of every gene in each cell of your body, and you get one from your mother and one from your father.

For example (and to oversimplify a lot), there are two forms of the gene for eye color, one for brown and one for blue. If you have both genes for blue, you will have blue eyes; if you have one or two genes for brown, you will have brown eyes. I will write B for brown and b for blue. So blue-eyed people have bb genes, whereas brown-eyed people can have BB, Bb, or bB genes. (The gene from the father comes first, so Bb means you got brown from your father and blue from your mother.)

Two blue-eyed parents can only have blue-eyed children, whereas two brown-eyed parents can have blue-eyed children if both of them are of the Bb or bB types, and both happen to give their child the b gene. (You probably know some exceptions: I am one, because my father had blue eyes and my mother had brown ones, whereas my own eyes are blue. But looking closely shows that there are flecks of brown in my eye color; blue here means 100% true blue.)

Moving on to the ABO blood type system. There are three kinds of genes here, A, B, and O. The A gene will cause a person to have red blood cells with the A protein in them, and the B gene will cause a person to have red blood cells with the B protein in them. The O gene doesn't do either one. So if someone's genes are AA or AO or OA, they will have A protein and be of blood type A. Someone whose genes are BB or BO or OB will have B protein and be of blood type B. Someone whose genes are AB or BA will have both proteins and be of blood type AB. And finally, genes that are OO will have neither protein and be of type O.

In your case, your your father's, brother's, and sister's genes are OO. Your mother is AB or BA and so are you. Your mother gave you either an A or a B gene, and you had to get the other B (or A, as the case may be) from somewhere. Your father is OO, so where did the other gene come from?

But that's not the whole story. Your brother and sister are OO, and your mother could not give them an O gene (since she has only an A gene and a B gene), so where did their O genes come from? One possibility is that you're wrong in thinking your mother was AB.

The most probable explanations are adoption, sperm donation, or something else that makes you and your siblings have different genetic parents. A DNA test of you and your siblings, preferably both of them, will nail this very reliably, and I would encourage you to get one. It turns out that about 15% of human beings, on average, are mistaken about their genetic fathers.

There is another possibility. There is another gene known as the H gene, which comes in two varieties: H (working) and h (not working). (The whole issue of ABO and H versus h does not make any difference to health, of course.) Neither the A nor the B protein can be made in your body unless you have at least one H gene. So people who have hh in their genes always appear to have blood type O, because no A or B protein is being made in their bodies even though the A or the B gene might be physically present. So your father might actually have an A or B gene to give you even though his apparent blood type was O, if he also had hh. However, the h gene is quite rare and the hh combination even rarer, so this isn't a very likely explanation.

Finally, she added:

I would be grateful for any help you can give me. I will always love him either way; I just need to know.

I replied:

Of course. As an adoptive parent whose daughter has always known that she is adopted, I know that genetics has very little to do with how we feel about our children or how they feel about us.

Update:

This post has obviously struck a nerve: it has gotten more comment than anything I've ever written. If you are going to comment to ask a question, three things, please:

  1. The Rh blood types (+ and -) are separate from the ABO blood types. The only thing to say about them is that two - parents will always have - children; every other combination is possible.
  2. Look in the following A/B/O chart first. Find your mother's blood type across the top, your father's along the side, and your possible blood types in the box.

ABABO
AA or OAnyAny but OA or O
BAnyB or OAny but OB or O
ABAny but OAny but OAny but OAny but O
OA or OB or OAny but OO

169 comments:

bae said...

Even more obscure than the H/h gene that causes people with A, B or AB genotypes to appear to be O because the H gene is involved in producing the precursor to both the A and B antigen, is the fact that chimeras and mosaics occur in humans as well as other mammals.

I won't get into the distinctions between the two terms, but the summary is that it's possible to have an entirely normal healthy person whose cells have different genotypes. In some cases, a mutation may occur in a somatic cell at some time during embryonic life or even later, and the descendants of that cell will have a difference from descendants of other cells.

The more interesting case is when two embryos fuse at an early stage of development, producing a single embryo which develops into a single individual. Mammals are amazingly robust in this case: even if the two embryos are of different sex, the result is a normal healthy adult of one sex or the other.

It's quite possible for the blood forming system in the bone marrow to descend from one embryo and the germ cells from the other. This person's offspring will reflect the genotype of the germ cell line embryo, while his or her blood type is determined by the genotype of the other embryo.

Chimeric mice were produced about 40 years ago, but no one knew how commonly these events occur in nature until the availability of DNA testing gave us a large sample. There have been a number of cases in which a child's *mother* "couldn't" have been his biological parent that have been determined to be caused by chimerism.

The upshot is that the brown-eyed child of two blue-eyed parents could still be their natural offspring, and one should always give people the benefit of the doubt. Even if such things occur only 1 in 100,000, that's not zero, and the case at hand might be an example of it.

Anonymous said...

What if the mother has brown eyes and the father has blue, but all three children had either blue or green eyes? What is the likelyhood that this could occur three times in the same family? Thanks in advance!

Anonymous said...

i had twin non identical girls, i am blue eyed husband was blue, i had affair got pregnant not knowing who was father , husband came back to me years later and said he was not father as was infertile. affair man (was ex boyfriend) he was brown eyed me twins are one blue eyed and other brown , any suggestions?? beginning to think each twin is different father??? had this on mind for 14 years do not want dna.

Anonymous said...

Can a B-ve father & B+ve mother give rise to B+ve son?

How is the blood group of the child formed?

John Cowan said...

Anonymous #1 and #2, eye colors are not like blood types: the inheritance pattern is much more complex. Blue eyes are recessive, but it has to be true blue with no flecks of green or brown. My mother had green eyes, my father had blue eyes; I have basically blue eyes, but if you look closely you can see the green flecks in them.

In fact, there is only one pigment in human eyes and that's brown. If you have a lot, your eyes are brown; if you have a medium amount, your eyes look green or violet; and if you have just a little, your eyes look blue or gray (for the same basic reason the sky does).

Anonymous #2: having twins by different fathers (which is called "superfecundation") is possible but not very likely as far as we know. It does happen in other animals (cats especially).

Anonymous #3: Rh positive is dominant, Rh negative is recessive, so children are most likely to be positive although negative is also possible if they got a hidden Rh negative gene from the mother. And since both parents are B, the child will be either B or O, since there can be no A gene to pass along. So what you got is exactly what you should expect.

Anonymous said...

HI
I have 2 children aged 9 and 12. My daughter is looking at me strangely because she is being taught in school that 2 blue eyed parents cant have brown eyed kids. Both my kids have brown eyes and both me and their father have blue. His are blue with white flecks and mine are blue with a yellow ring. They are both his children so 2 blues can make a brown or 2!
Natalie Australia

John Cowan said...

Anonymous #4, take a look at my earlier comment. The brown ring in your eyes shows that you have the dominant brown-eyed gene, which for some other reason is only being expressed in the part of your iris where the ring is. So it's not surprising that your kids' eyes are brown -- evidently they didn't inherit the "ring" gene(s).

Anonymous said...

hi.. my blood type is 0+ and my husband swears he has o-. it said it on his emergency wrist band when he was a kid. but we recently had a baby who's blood type it A+. Now his father has A= And his mother is An O and his sister is and A+ also. I have a feeling he is an A+. but if test came out if he is an 0- can that be possible to have An A+ baby??? I mean it is definitly his. can you help??

John Cowan said...

It's easy to get blood typed, and it's also easy to get a DNA test, though more expensive.

Anonymous said...

if a baby was born through incest (father + daughter) And both have O blood. is it possible for the baby to have A+ blood or would it have to be O. this question is for a paper im writing and can find any answers..

John Cowan said...

Please read the original posting with attention! I love explaining things, but I draw the line at doing people's homework for them.

Anonymous said...

I want to know whether if the parent of the child is B-ve and O+ve can the childs blood group of A+ve

Anonymous said...

I really don't understand blood types so here's my question

If the mother is A+ and the father is A+ is the baby also A+?

Also, if the mother is A+ and the father is 0- can the baby be A+?

It's very confusing....

Anonymous said...

hi I just wanted to know if both parents of a child has a blood type of O is there any possiblity that their children would have a diffrent blood type such as A, B or AB? Thanks in advance.

Anonymous said...

if i am rhesus negative same as my mum but my dad is positive i also have a stepsister who is rhesus negative too but we have not got the same dad i dont think but it has come to light that my mum was unfaithful while married to my dad with the father of my stepsister do you usually get the blood group off your father as my dad is positive

Anonymous said...

hi my mother is A+ and my dad o- I am A neg, is my father my real dad.??

John Cowan said...

Okay, five new Anonymouses since my last reply. This seems to be my most popular page -- go figure.

Everyone, please remember that I can only go on the facts as you give them; it may turn out that you're wrong about people's bloodtypes. Please recheck, and get DNA tests, before making any life-changing decisions or accusations.

Anonymous #7, B and O don't make A. The B person is either BB or BO, and the O person can only be OO, so there is nowhere for the A gene to come from.

Anonymous #8, your first question asks about A and A. Well, either A or O is possible, depending on whether either parent has a recessive O gene to give the child. A is more likely, though. Positive is dominant, negagtive is recessive, so you'd expect a plus in either case.

Your second question is whether A and O parents can have an A baby. Again, both A and O are possible. Positive is always expected unless both parents are negative.

Anonymous #9, if both parents are O, then all children must be O, except for the Bombay syndrome that I discussed before where people appear to be O even though their genetics are something else.

Anonymous #10, if you are negative your biological parents are both negative, although that does not prove that your biological father is the same as your half-sister's -- it might be someone else altogether.

Anonymous #11, something is wrong with your story. Either the bloodtypes are wrong, or your mother is not your biological mother. (It can happen; my father-in-law didn't find out that his mother was really his stepmother until he was 21 -- his biological mother had died when he was only 2.)

Anonymous said...

is it possible to have a baby and the blod type is different from both parents? my sister had a baby and her type is O+ and her hubby is A+..and baby is A-. Was my sister unfaithful or does this sometimes happen? we do know that there are A- blood types in the family though, such as an aunt.

Anonymous said...

A mother with O+ and father with A+, then can the child be A-...??

Anonymous said...

Can a couple of the same blood group e.g O get a child without agglutination?

Anonymous said...

i hav one question plz tel if father is O+ve and mother is AB-ve then they can hav O-ve child

Anonymous said...

I have O pos my hubby has o pos blood both of our girls are o- . So was his father o- and his mother a pos, both of my parents o pos. Question I had a one night stand right before we I got pregnant with one of them . I know O - is rare blood type what do you think the odds would be for the two girls to have differant fathers.

Anonymous said...

i am O pos and my husband is A pos..what is our babys blood type. Or what are the possibilities of our babies blood type. Are there any tests a person can do before birth to find out the blood type of our baby. Anonymous

Anonymous said...

My brother has two childern the first child has a blood type a possitive. The second child is o possitive. My brother is o possitive,his wife is ab negative.Is there any way this child with a possitive is my brothers child.This has been a wonder to me for some time both of our parents are o possitive.

Mark S. said...

OK, John thought maybe I could answer some of this latest batch.

Two things regarding what John said that make me wonder, though:

(1) in answer to Anonymous #9, John said that "if both parents are O then the kids have to be O, except for the Bombay syndrome..." (the H/h thing was news to me, incidentally). So I could imagine one parent who was, say, AA or AO *but* hh and thus genetically type A but apparently (phenotypically) type O, and the other parent a "true" type O, with fully functional H alleles. So an offspring could get an A from the first parent (even though that parent tests out as O), and a working H from the second parent, which would then seem to "activate" the A allele which the parent wasn't expressing, thus an A child from O parents. Does this make sense? Obviously it would be pretty rare.

(2) Anonymous #11 said "hi my mother is A+ and my dad o- I am A neg, is my father my real dad.??" John answered that there was something wrong with the story; either the blood types were wrong or the mother wasn't really the mother. I don't see the problem. If the mother was A+ but heterozygous for Rh factor, it could certainly happen. That is, the mother had one Rh+ allele and one Rh- allele. Since Rh+ is dominant, she would be dominant. If one child inherits the Rh- from that side and the Rh- from the O- father, then the child certainly could be A-

OK, on to the latest batch...

Anonymous #12: As above, that should be possible, if both parents are heterozygous for Rh factor. Did any of their parents have a "negative" blood type? The odds are against this kind of thing, but against it the sense of "it happens one time out of four" or something, so it really isn't that strange.

Anonymous #13: This is the same question as #12.

Anonymous #14: Sorry, I don't understand your question. What do you mean by "agglutination"? My knowledge of the subject isn't enough here.

Anonymous #15: O+ father and AB- mother... I can't see how an O- child is possible. The mother has to be passing on either A or B, either of which is dominant over O. Unless there's weird Bombay syndrome stuff happening, this shouldn't be possible.

Anonymous #16: It is certainly possible that your husband is the father of both of them. He was certainly heterozygous for Rh factor and even though both your parents were Rh+, you still might be heterozygous if one of them was. I won't speculate odds, though, since I don't really know the frequencies involved.

Anonymous #17: Your baby's blood type is probably going to be A+, with O+ a definite possibility. It's not very likely (but definitely possible) that the baby would be Rh-negative. Type B or type AB can't happen under these circumstances (unless there's something very rare happening). I'm pretty sure there are tests that can be done to check fetal blood type.

Anonymous #18: Actually, it's the O+ child that makes me wonder. The A+ child definitely could be your brother's. Remember, in order to get AB, you have to get one from each side. So the fact that the A+ child isn't the same type as either parent isn't surprising: the father didn't have A or B to contribute. The O+ child is the big question, though. The mother had to be contributing an A or a B, either of which would dominate the blood type. I don't see how the child could wind up with type O if she really is his mother. As usual, remember that life is an awfully complicated thing, and unexpected effects can happen.

John Cowan said...

Thanks, Mark. I appreciate the assist, and you've got Anon #9's situation exactly right.

You're also quite right about Anon #11: positive mothers can have negative babies, if both parents are +-; this also affects my reply to Anon #8.

As for Anon #14, "agglutination" refers to the clumping of red blood cells that happens when there's a conflict in the ABO system. I don't understand the question either, though.

Anonymous said...

Hi... Well i always had this doubt and wanted to clear it... Is it possible to have normal babied if both the mother and father have the same blood group say O+ve... Please help

Anonymus 17

John Cowan said...

"Anonymous 17" (really #19): yes, of course. ABO blood groups can mix and match, and can't harm the baby in any way. The only risk comes from Rh disease (negative mother, positive baby), and that can easily be prevented now. Read this.

Anonymous said...

Hey John

Thanks so so much.....

Anonymus 17

Anonymous said...

can we have baby if my blood group and my wife blood group is o+ please tell us

John Cowan said...

Anonymous #20 (sigh): Yes, provided you have sex.

Anonymous said...

I am O+ and my husband is O- does our child have to have O+ or O- blood type?

Anonymous said...

Anonymous #21: O+ is to be expected.

Anonymous said...

everyone in my family is A- i am a O+ is this possible? mum says i am their daughter (she blames the gypsies that swapped me at birth)

John Cowan said...

Anonymous #22: There is no problem with being O if your parents are both A: they could both be AO, in which case there's a 1 out of 4 probability that a child would be O.

Being + when both your parents are - is unlikely, though.

Anonymous said...

thanx john they are a+ i once had a doctor that told me i couldnt be related (i do think the gyspies did something though i'm a completely different breed to my family) thanx again

Anonymous said...

Hello,

I am 0+ and my wife is 0+ so can you please tell me if there would be any problem in my wife pregnancy or for the baby?

Thank you,

Wilson

John Cowan said...

Wilson: probably not. Go see a doctor instead of trusting me.

Anonymous said...

I have O- blood type, My mother says she has RH-, now the real question is who is my father? Blood type RH+, A+, or B+. I would be grateful for any ideas.
Faith

Anonymous said...

can we have a baby if my blod group is A+ and my husband's blod group is A-?

Anonymous said...

There's 4 blood group A B AB and O. Your blood type is base on if you have an antigen on your RBC (red blood cell).An example.... If you have both A&B antigen on your blood cell then you is AB and the RH factor gives you your type either positive + or negative- , which result in either AB+ or AB-. All women who is RH negative should have the shot of RHOGAM when the father is postive due to miscarriage and death in yiour baby, 2shots are administer when pregnant.the bottom lines if Dad is O and Mom is AB then the baby is O as well and in other cases Dad is O and Mom is AB and baby is A+ the question is who your baby daddy. I hope this will answer many concerns about blood groups and type. It made a different in my life and during school.

Anonymous said...

I have been reading many pages on this subject over the past few days and here is my question. My mother is O neg and I am B neg (this is certain). However, I believe my 'father' to be A pos. If I am right, this combination is impossible isn't it? He must be either B pos, B neg, AB pos, or AB neg to be my true biological father I believe.

Katie said...

I actually had a question about an earlier post of yours you responded to:
"hi my mother is A+ and my dad o- I am A neg, is my father my real dad.??"
with:
"Anonymous #11, something is wrong with your story. Either the bloodtypes are wrong, or your mother is not your biological mother. (It can happen; my father-in-law didn't find out that his mother was really his stepmother until he was 21 -- his biological mother had died when he was only 2.)"

Couldn't it be possible for the mom to have both a positive and negative allele? Since the father is negative it would definatly pass on as negative, so couldn't the child be A- if the mom passed on the negative gene?

Goldenchild78 said...

I’m trying to figure out if I am the father of an ex-girlfriend’s baby. When I first started seeing her she was also with another man which is when she became pregnant. Which she told me she couldn’t have one. I wanted to have an amnio paternity test done and she said her doctor would no longer be her doctor if she had one. Seems a little fishy since shes 29 and dont the doctor usually push for it if you are 30. I also have a realtive with spina bifida and another relative with autism.

We had a falling out about half way through the pregnancy primarily because I didn’t trust her. She has since had the baby and is on to another man now and wants me to be now part of the Childs life. I asked her what she and the baby’s blood type were and she stated that she and the baby are both AB-. I myself am O+ or that’s at least that’s what my donor card says. Would they check for Bombay syndrome? So from what I read on this site the baby could not be mine unless it was one of those extremely rare instances correct?

I trying to see if I should go get a lawyer and force the paternity test. She is a very deceitful person and I believe she has been lying to me all along about the baby being mine. Please let me know what you think any more information would be great on this matter.

John Cowan said...

Faith: There's no reason, based on this evidence, to suspect that your father is not your father.

"Rh+" and "Rh-" mean the same as just plain "+" and "-", so what we know is that you are O-, your mother is A-, B-, AB-, or O-, and your father is A+ or B+. Rh is like ABO, but simpler: people with two minus genes show up as -, whereas people with one or two plus genes show up as +.

Consequently, your mother is minus-minus and your father could be plus-minus or minus-plus and gave you a minus gene, leaving you minus-minus or -. So far so good. Likewise, your father could be AO or BO, giving you an O from him and an O from your mother (since we know nothing about what your mother had on the ABO side).

Anonymous #23: No problem having a baby. The ABO genes don't affect pregnancy or birth, and the issue with + and - affects only - mothers having their second (or later) + baby -- they can become allergic to the baby's + gene, essentially. This condition is routinely screened for, anyhow. You are +, so no problem.

Anonymous #24: Most of what you say is right, but you are wrong to say that an O father and an AB mother will have an O baby. AB mothers will give their children either an A gene or a B gene, so unless Bombay syndrome is present (see the main post) the outcome will be A or B.

Katie: Quite right; my answer to Anon #11 was wrong, as acknowledged in my answer to Mark.

Goldenchild78: The only verifiable fact (to you) in your whole story is your own blood type, unfortunately. Since you don't trust the woman in the story, you have no reason to trust her report of her blood type, or her baby's either. So it's up to you. If you want to support the child (but not if you are not the genetic father), or if the mother is trying to get money from you, then you need the DNA tests and should get the lawyer. (I am not a lawyer; this is not legal advice.)

Anonymous said...

I am B+ and my wife is A+ but my baby is O+. Is it possible?

John Cowan said...

Anonymous #25: Sure. Positive is dominant, so that's fine, and if you are BO (or OB) and your wife is AO (or OA), then each of you could contribute an O gene to your child.

Anonymous said...

I am B-. My mother is O+. My father is A+. Is there any possibility that he is my biological dad? If not, my next step,to be sure, is DNA testing.

John Cowan said...

Anonymous #26, it's possible but not likely. Get the test, but remember: the male who raises you is your father.

Anonymous said...

If my mother blood type is A+ my father is O and mines is AB is he my father

John Cowan said...

Anonymous #27: maybe not. Get a DNA test!

Anonymous said...

Both, my mother and father are A+. I am A-.I have 2 full blooded siblings by these parents both A+. one older one younger. What are the odds of 2 people with A+ having A-?

SC said...

My mother is B-ve and my father is A+...I am AB+ with green eyes and they both have brown eyes...is this possible? SC

John Cowan said...

Anonymous #29: Normally, two Rh+ parents don't have Rh- children. Talk to your parents.

SC: No problem.

Anonymous said...

hi john
iam O-ve and my husband is also O-ve. will our babies be having any abnormalities?

John Cowan said...

Anonymous #30: Not for that reason, certainly.

Anonymous said...

I was wondering... if I am o positive and my wife is A positive, could we have a child with a negative blood type?

Anonymous said...

If I am B+ and my husband is O+ how can we have a daughter who is A+? and please he is my daughters father and we are positive about blood types.

karen123 said...

hi i was wondering if you could help me! my mum, dad and sister are all O negative whereas im A positive, can this be possible?

Anonymous said...

My blood type is AB+ and my husband's blood type is B+,is our blood types compatible if we are going to have a baby?I mean does in affect to our baby?

Anonymous said...

We discovered the other night, I am O+ blood type, my sis is A+ and my mum is O- , what would my dad have to be for me and my sis to both have the same father?

jill said...

please can u help me my father had ab neg my mum o pos, i am b neg my brothers are o pos, are my parents our parent

Anonymous said...

could you help me my mother is o+ my father is A+ i am A- is my dad my dad ??

aksh said...

i m B+ and my would be husband is O- is it safe for us to marry and have kids?

Anonymous said...

can a woman have o- with rh fatcor and a man with O+ can they have a A+ baby is this possible?

Anonymous said...

I am A+ve, my wife is B+ve. Can the child have O+ve blood group??

Thanks in advance.

Anonymous said...

I have read ALL the posts and still have a question. My husband is O and I am A but my son just found out he is B. Could this be true? How do I find out if one of us has a 'B+' protein or a hidden gene that may produce a 'B' child? Could the blood bank have miss typed him? This has me concerned!!! I have also been told I am 'A-' and 'A+' at two different times. Does that make a difference?

Anonymous said...

I just had a baby that is o+ .I am A-.What would her father's blood type be to make her o-? Thanks

Anonymous said...

ihad just posted a comment i want to know how is my daughter o+ when i am A-?what would her fathers blood type be?

Anonymous said...

I am 28 Year Male with Blood group B+. can I marry a girl with Blood group O-? What are the probable complications during pregnancy?

Pearl said...

I have just found my biological brother, we know for sure we have the same Mother, (our birth certificates etc. support this) we feel we have the same Dad (timing and logic make us think so) However I have B+ blood and he has O+ blood. Our mother is Cuban and I know that O+ is most common in hispanics. Is it possible still that we could be full brother and sister, that my Dad was b+ and I got his blood type?

Anonymous said...

I have A positive blood, my 3 younger siblings have A negative blood. My mother was pregnant when she got married. I think She is O positive and my Dad was A negative. Does this mean we still could have the same father?

Andrea said...

Hiya please help me i need some answers my Mum is B+ and my father is O+ is my dad step or my real please help

John Cowan said...

Anonymous #31 said:

I was wondering... if I am o positive and my wife is A positive, could we have a child with a negative blood type?

Not likely.

Anonymous #32 said:

If I am B+ and my husband is O+ how can we have a daughter who is A+? and please he is my daughters father and we are positive about blood types.

That's not likely either, though if your husband is a disguised A because he has the h gene (see the original post) it's possible.

karen123 said:

hi i was wondering if you could help me! my mum, dad and sister are all O negative whereas im A positive, can this be possible?

Same story for you: either your mother or your father could be a disguised A. Alternatively, you could be adopted (or adopted by one parent only), or the product of natural or artificial insemination by a third party.

Anonymous #33 said:

My blood type is AB+ and my husband's blood type is B+,is our blood types compatible if we are going to have a baby?I mean does in affect to our baby?

It shouldn't be a problem. Ask your doctor.

Anonymous #34 said...

We discovered the other night, I am O+ blood type, my sis is A+ and my mum is O- , what would my dad have to be for me and my sis to both have the same father?

A+

jill said:

please can u help me my father had ab neg my mum o pos, i am b neg my brothers are o pos, are my parents our parent

You could be, certainly. Your brothers, probably not: your mother gave them an O gene, but your father could not, since he had only A and B genes.

Anonymous #35 said:

could you help me my mother is o+ my father is A+ i am A- is my dad my dad ??

No reason to think he isn't. - is recessive, so both your parents could have been + but still have a - gene to give you.

aksh said...

i m B+ and my would be husband is O- is it safe for us to marry and have kids?

Sure, unless there is homicidal insanity on one side of the family or the other.

Anonymous #36 said:

can a woman have o- with rh fatcor and a man with O+ can they have a A+ baby is this possible?

Very very unlikely.

Anonymous #37 said:

I am A+ve, my wife is B+ve. Can the child have O+ve blood group??

Absolutely. O is recessive, so you could each have an O gene to give the child.

Anonymous #38 said said...

I have read ALL the posts and still have a question. My husband is O and I am A but my son just found out he is B. Could this be true? How do I find out if one of us has a 'B+' protein or a hidden gene that may produce a 'B' child?

Not that I know of. There's a mistake somewhere.

Could the blood bank have miss typed him? This has me concerned!!! I have also been told I am 'A-' and 'A+' at two different times. Does that make a difference?

No, except that it suggests the blood banks aren't being any too careful about + or -. This is not normally a concern for blood donation, only for incompatibility during pregnancy. In any case, donor blood is always cross-matched with the recipient's blood to make sure there are no subtle difficulties.

Anonymous #39 said...

I just had a baby that is o+ .I am A-.What would her father's blood type be to make her o-?

It could be any of A, B, or O, but definitely +.

Anonymous #40 said:

i had just posted a comment i want to know how is my daughter o+ when i am A-?what would her fathers blood type be?

A+ with a hidden O gene (which you have too).

Anonymous #41 said...

I am 28 Year Male with Blood group B+. can I marry a girl with Blood group O-? What are the probable complications during pregnancy?

Your first child will probably be fine. Your second child, if any, might have a problem. Your doctor will advise you about this -- blood typing of pregnant women is routine.

Pearl said...

I have just found my biological brother,

Congratulations!

we know for sure we have the same Mother, (our birth certificates etc. support this) we feel we have the same Dad (timing and logic make us think so) However I have B+ blood and he has O+ blood. Our mother is Cuban and I know that O+ is most common in hispanics. Is it possible still that we could be full brother and sister, that my Dad was b+ and I got his blood type?

Yes, it is. If your father had a B gene and a hidden O gene, you could have gotten one and your brother the other.

Anonymous #42 said...

I have A positive blood, my 3 younger siblings have A negative blood. My mother was pregnant when she got married. I think She is O positive and my Dad was A negative. Does this mean we still could have the same father?

Yes, definitely. If your mother has one + and one - gene, then your brothers could have gotten the - gene (along with the - gene from your father, the only gene he has) whereas you got your mother's + gene.

Similarly, your father could have an A gene and an O gene, and all of you got the A gene. No problem there.

Andrea said:

Hiya please help me i need some answers my Mum is B+ and my father is O+ is my dad step or my real please help

There's no way to tell, because you didn't give us your own blood type, you silly person. Try again.

Curious said...

When my daughter began giving blood, she mentioned that she's AB+. Both her father and I are A+, and he's definitely her biological father. My daughter said that she'd asked a nurse about that, and the nurse told her that both her father and I must have had a recessive gene. What gene would that be?

John Cowan said...

Curious: Ya got me. That shouldn't be possible. But see the first comment above.

Curious said...

Thanks for the reply. I know she's not adopted, because I gave birth to her. And her father and I were still honeymooning when I got pregnant three months after the wedding, so I wasn't sleeping with anyone else. Maybe one of my parents and one of his had a recessive B?

My daughter's not concerned, and she hasn't brought it up since we first discussed it, but I'm Curious.

judy said...

I have also just found a long lost 1/2 (we think) brother and sister.
My blood type is AB+, my sister is A+, her mother was AB+ & we think our father must've have been B+. As I remember,the woman I always knew & loved as my mother was O+, I think. I can't seem to find any records as she passed away in 1989. Is there anyway she could be my real mother if she was O+? Would a DNA test of my sister & me be able to tell if we are full sibs or 1/2?
There are some family stories that say my mother wasn't my birth mother - but all the story tellers are long since gone. I still have my mother's ashes.
Thanks in advance for any help or suggestions you can give me.

John Cowan said...

Curious:

I have no clue. I assume it was a polite expression of disbelief.

Judy:

Your sister's father could have had any blood type whatsoever.

You are a bit vague about your mother's blood type, so I wouldn't go assuming anything. If she was indeed O+, then she could not have been your biological mother (since O parents have no A or B genes, and you got an A from one parent and a B from the other) unless one of the odd circumstances discussed in the original post applied.

Anonymous said...

hi... i am confused. hope someone could perhaps help.
i have a 5yr old healthy son.
i recently miscarried at 6 wks, with no explenation.
i know i am orh - from my first pregnancy. could my blood group have something to do with my miscarriage and if so how can this be prevented as the gynie i saw was not very informative.
ys.

Jennifer said...

I hope you can help. Back in 1996 I had a miscarriage and was given the Rho Gham shot. I was told that I was RH-. Then in 1997 when I donated blood the card that The American Red Cross sent me said I was O+. How can this be possible? Then in 1998 I gave birth to a normal, healty girl. If I was Rh-, shouldn't they haven given me another Rho Gham shot? Well they didn't. Then in 2001 I had another daughter. See is now 6 years old and has developmental problems. Then in 2005 I had another daughter who is normal and healthy. Could my middle daughters problems be because of my blood type? Any help will be greatful.
Jennifer

Anonymous said...

I am blood group A negative. My mother is O Negative and my sister is A Posative would that make my dad A positive if so would i be his real daughter.

dragonfly said...

hi im an a rhesus negative and both my parents are a positive i was told years ago by doctors that they cant be my parents yet my grandma is rhesus negative can this please be confirmed thanx dragonfly x

John Cowan said...

Anonymous (I'm not going to number you people any more): I doubt it.

Jennifer: Looks like someone made a mistake somewhere, but there's no telling who. Developmental problems are common enough that without conclusive evidence they can't be pinned down.

Anonymous: There's no reason to think that your dad is not your biological father, in which case his blood type would indeed be A+.

Dragonfly: A negative child can have positive parents, because positives can have either ++ or +- genes; if each of your parents is +- (which looks the same as +) then they could each have given you a - gene making you --.

Anonymous said...

igpavmy sister and brother have ab pos. blood group. my mother was ab. pos and my dad was o pos. and my blood group is b neg. i would just like to find out is it possible

John Cowan said...

Anonymous: An O father can't have AB children, so whatever else is or isn't true, your dad cannot be the biological father of your siblings.

Carolyn said...

Hi. i am doing a little research because my father needs a kidney transplant. He is O+. his sister offered, but cannot, as she is AB. Am i right in infering that if they are full siblings, their parents (my grandparents) would both have to be from the blood group B?

John Cowan said...

Carolyn: Your grandparents have to be one A and one B, or your aunt couldn't be AB. Since your father is O, that means that one parent had an A and an O gene, and the other parent a B and an O gene.

Kay said...

Hi,
My question is a little bit different. My blood type is A- RH- and my husband is B+ and we had twins and in the hospital I was told at first that my twins were identical but later after taking them home found their blood types to be O+ and AB+ and at one point a nurse I mentioned that to told me this is not possible but later said oh ok I can see how this could happen but had a skeptical smile which gave me the feeling she thought I cheated on my husband and I found insulting. Is there a mix up somewhere or could they have given me one wrong baby when we came home?
Thanks in advance for taking the time to answer my question. K

John Cowan said...

Your twins are not identical based on their blood types, but fraternal twins can look strikingly alike. If you are A and your husband is B, or vice versa, then there is no reason to think that the twins are not yours. (Having twins by more than one man does happen, but is extremely rare -- google for "superfecundation" if you're curious.)

Kay said...

Hi,

I knew I my twins were my husband's children I never suspected otherwise because there had never been anyone else. I had wanted to know why a nurse would tell me its not possible for a mother with A- blood and a father with B+ to have twins who were AB+ and O+. But thanks anyway.
Kay

Anonymous said...

Is there any possible way for the following to occur; mother is B+, father is AB+ = child is O+ ?

John Cowan said...

Anonymous, the answer is no: an AB father has no O gene to give to his child, and an O child requires two parents with O genes (not necessarily two O parents). Again, subject to the usual qualifications.

Anonymous said...

My mother is O rhesus negative, my sister is also O rhesus negative, My other sister is AB positive and my father is also AB postive. I am A negative, could it be that we are not really related? is it possible i am not my fathers child? or that my sisters are not my fathers real children? thanks in advance.

John Cowan said...

Anonymous: you could be the biological child of both your parents, but your sisters could not. An AB and O couple can only have A or B children.

Anonymous said...

Thanks very much John, and everyone thought i was the one who wasnt related! i think a few dna tests are in order, thankyou very much again.

Dave said...

Hello, a woman claims a child is mine. The mother is A- and the baby is O-. I am O+. Wouldn't the father have to be A or O negative? From what I read here, the positive gene is dominant so the baby would have to be O+ if I was the father, right?

John Cowan said...

Dave: That you aren't the father would be the way to bet, but a DNA test is simple and definitive.

Nancy Greer said...

Is it possible for two people who are 0+ to have a 0- Rh child.

Anonymous said...

i am o pos dad is a neg and 3 of our 5 children are a pos its called cumes pos when this happens . I know im not spelling it right but this is a true thing and dad is dad my sister didnt believe it so we did a dna test to prove it

Anonymous said...

Hi, yes, I belong to the large Anonymous family of the Internet. I came here from the "Flow, Stuckness, and Interruptions" post (that I plan to show to my boss), and was intrigued by one of the comments. Being the proud father of 3, I don't really mind about mine or their blood type as I think of them as my child, no matter what.

Besides that, Mr. Cowan, I think It would be interesting (and probably a lot less time consuming than answering almost all the comments, a thing that you seem to enjoy anyway) to craft a small script that calculates the possibilities of the offspring given the blood type of the parents.

Anyway, I find your blog posts very interesting and amusing, and this blog will land in seconds in my feed reader. Regards, Erico.

vickim said...

hi John

Can you help me please? I was place in foster care at an early age and have recently found my siblings. However after chatting my sister informed me that she was A-ve I enquired and I am +ve. Does this mean we have different fathers? As i am sure 2 -ves do not make a +ve. Do they???

please help

vickim

John Cowan said...

Nancy Greer: Sure.

Anonymous: I'd expect some of your children to be A+, with A and + genes from their father, an O and - genes from you.

Erico: I'm glad you think of your children as yours no matter what, and that you like "F, S, and I". Note the chart at the end of this post, so people who ask questions since I added that chart clearly want a personal touch -- and the rate of questions has slowed down, fortunately.

VickiM: Biological-family reunions are a Good Thing in general. It's true that two Rh-negative parents can't have an Rh-positive child, but any other combination can have both negative and positive children, so there is no reason to think that you and your sister have different fathers.

Anonymous said...

i am b plus and my brother is o positive could we have different fathers

John Cowan said...

Anonymous: You might have different fathers, but there's no reason to think so without more information.

laura said...

hi my blood type is b+ and my brothers in o positive i no that my mother did have an affair with my fathers cousion and is not sure of which one is my father. idont want to ask my father for dna even though he knows and his cousion died 8 years ago so im trying to find out myself as i want to know could we be through brother an sister with different blood types. thanks

John Cowan said...

Without either your mother's blood type or your father's, there's nothing to go on.

laura said...

hi if i got a dna with my brother would it show if we were true siblings thanks

John Cowan said...

Laura: Yes.

Duane said...

Is it possible for an AB- mother and O+ father to have an AB+ child?

John Cowan said...

Duane: Not normally. An O parent has to have two O genes, and so can't pass either an A or a B to the child. See, however, the H/h discussion in the post and the remarks in the first comment.

Stephanie said...

I have 2 partners and one of them is A+ & the other is B+ and my son is o. Can I know who is the father?

John Cowan said...

Stephanie: You don't mention your own blood type, but either man could have an O child. DNA testing is your friend.

babyblusmurfett said...

Hi I found out a few years back that my dad may not be my dad. My sister has O- I have O+ I know my dad has O+ and I know my mom had O but im not sure if it was -or+ The man i was told could be my dad is O+.

babyblusmurfett said...

oops sorry about that my dad is O- the man they said might be my dad is O+

jcowan said...

babyblusmurfett: You had to get the + gene from either your father or your mother. Since you don't know if your mother was + or -, there's no knowing if you got it from her. If she was +, you can't decide between your two possible fathers. If she was -, it had to come from the person you were told might be your father, not from the father who raised you.

yqyq said...

Can both parent with O+ blood gave birth to a kid with B+ blood? Their 1st kid is O+ but 2nd is B+.

acute said...

my father is B+ and my mother is A+. iam O+. do you think this is possible?

margisonlol said...

if mum is o+ and dad is b+ could the baby be ab- ?

cynthia said...
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cynthia said...

Hello my Mother is an A+ and my Father is an O+. My brother is also an A+....I am a B+, what's up with that? Thank You so much for answering all these questions it is so very selfless of you~ Cyndi

John Cowan said...

yqyq: Probably not. A DNA test will be definitive.

acute: Yes, absolutely possible: both your father and your mother could have given you an O gene.

margisonlol: The A gene has to come from somewhere, and neither an O nor a B parent could carry it.

cynthia: In your case it's the B gene that has to come from somewhere.

All: Talk to your parents, especially your mothers. You may be adopted and they've been afraid to tell you (or, for older folks, advised not to by misguided social workers. Or there may be other reasons. In my opinion, if you are old enough to ask, you are old enough to know.

cynthia said...

Dear John, Thank You! My Mother will not admit a thing and she will probably take it to her grave and I have no contact with the man she claims to be my father since I was 3 months old.... Thanks for your attention on this matter. So, that is that then you can't get B+ from A+ and O+ then? I am satisfied and content....Have a wonderful life! ~ Cynthia

disappointed said...

Throughout my life my mother has told me I have had four different fathers. I was raised by a wonderful man who married my mother when I was six months old. He was my daddy, I was an only child. I adored him and he adored me. A relatoinship my mother was always jealous of. After my daddy passed away, my mother married the one who is suppose to be my biological father. They have been married for about ten years. I have never felt a connection with him. I told him it was like my mother married a stranger and he could never take my daddy's place. My mother became ill a few years ago and had to be given blood. My mother and biological father joked about their blood type. Can't remember which was which, (I will do more digging)one was A+ and one was B+, I am O+. But, I have alaways thought the third man(who is O-)she had told me was my father. In fact at thirteen and my friend, a boy was fifteen, we were inseparatible best buddies, they (my mother, his father) sat us down and told us we were brother and sister. Talk about screwing up a kid! I recently found the friend and he too remembers the conversation. I'm feeling very lost and having an identity crisis! PLease help.

John Cowan said...

Disappointed: I don't quite see where the four different men came in — you only talk about three — but you could perfectly well have any combination of A+, B+, or O- parents. In fact, the only thing that's excluded is having two Rh-negative parents.

As for warning a 13-year-old girl and a 15-year-old boy that they are blood relatives, it seems to me an entirely sensible thing to do, and it's only a pity it wasn't done sooner. In any case, you know who your mother and father were: the ones who raised you. If your biological father is a bit of a mystery, probably 20-25% of humanity are mistaken about their biological fathers, only they'll never even suspect it. So I recommend doing your best to comfort yourself.

John Cowan said...

Disappointed: I don't quite see where the four different men came in — you only talk about three — but you could perfectly well have any combination of A+, B+, or O- parents. In fact, the only thing that's excluded is having two Rh-negative parents.

As for warning a 13-year-old girl and a 15-year-old boy that they are blood relatives, it seems to me an entirely sensible thing to do, and it's only a pity it wasn't done sooner. In any case, you know who your mother and father were: the ones who raised you. If your biological father is a bit of a mystery, probably 20-25% of humanity are mistaken about their biological fathers, only they'll never even suspect it. So I recommend doing your best to comfort yourself.

shubha said...

Hi I am simran..

My mom is B+ and my dad is A+.. And now I got to know that I am A-.. Is it possible that A+ and B+ can produce A- baby?

Please suggest..

John Cowan said...

Shubha/Simran: Yes, perfectly possible. Your father gave you an A and your mother an O, so you are an A. Both your parents are mixed + and - (which comes out +) and they both gave you an -, so you are -.

Undiscovered_Talent said...

Hi. My Mother's blood type is B+. My fathers blood type is O (im not sure if its - or +) but I KNOW that it is in fact O. All of my siblings are either O or B+. I am the youngest child of 5 and my blood type is AB+. Is that actually possible?? I have read all of the posts and I am so confused. Can a B+ mom and an O dad have an AB+ child???? :(

John Cowan said...

Undiscovered Talent: Neither your mother nor your father had a B gene to give you, yet you are AB, so (barring the possibility that your father is hh, as explained at the end of the original post), you had to have a B or AB genetic father.

Undiscovered_Talent said...

Wait. My mom is B+ so yeah they had B genes to give me. Its the A gene that isn't given anywhere. I believe you might have read my question wrong....?

John Cowan said...

Sorry, that was a brain fart on my part. The argument is the same, however: there's no source for your A gene.

As I've repeatedly noted up-thread, your true parents are the people who raise you (disclosure: I'm an adoptive parent), and 20-25% of people are not the genetic offspring of their fathers.

kathyratcliff said...

I AM AB-. MY MAN WHO RAISED ME WAS B-.NOT SURE WHAT MY MOTHERS BLOOD TYPE WAS,I THINK MAYBE A OR B... I WAS ALWAYS TOLD HE WAS MY FATHER BUT NOT SURE.. COULD I HAVE AB- FROM HIM BEING B-

september said...

Hi, I read Curious' post about an A+ mum and an A+ pop making an AB+ kiddo and I want to know if (though rare) might be a possibility... I am an AB+ offspring of 2 A+ 'rents. I know that they are my 'rents...mum was with no other and I believe her...her and I have spoken about the anomaly of this and I look just like the mix of them both...So, what do you think?? Does someone need to do a study on AB+ enigmas?? or should I try to find out who the nurses switched me with at birth??

John Cowan said...

Kathy Ratcliff: Sure. Your being AB suggests that your mother was A. Two Rh+ parents can have an Rh- child if they each have a hidden Rh- gene to give her.

September: Your B gene had to come from somewhere.

anairb said...

So I am 16 yrs. old and I was told by doctors I have a rare blood type. But every article I've looked at has confused me and now I am starting to wonder. In my blood the Rh factor comes into play. They told me I have an auto-immune deficiency which kind of means I have the "wrong" blood type. My body sort of attacks itself when I am sick.(Just for tips I had (SJS)Steven Johnson's Syndrome when I was 10.) I'm pretty sure my mother is O+ with the -Rh && my father was A+ with +Rh;(passed away when I was young);And so I came to be A+ with the +Rh. I don't really know much about blood types and I'm just really confused?? Can someone give me advice or tell me what's going on?? Thanks!!

anairb said...
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mTrucke5710 said...

My husband and i have two children. I know my blood type and our sons's blood type, but my husband has no clue as to what type he has. Also when he was born they had issuse on paternity of his father, but his dad refused to get testing done! If im A+ and one son is A+ and the other is O+ blood type, what kind would that make my husband? And what kind would that make his parents have to be? He would like to know so that he can be put to ease about his dad possibly not being his dad. PLEASE HELP!

John Cowan said...

Anairb:

Rare blood types usually have nothing to do with the ABO or Rh systems, and there are hundreds of them. Without more information, I can't tell you anything else.

mTrucke5710:

Your second son is O, which means that both you and your husband gave him an O gene. That means you are AO rather than AA, but the only thing we can say about your husband is that he is not AB. He could be AO (which comes out A), BO (which comes out B), or OO (which comes out O). Consequently, there is nothing at all we can say about his parents' blood types. Your husband will have to live with the uncertainty.

Sorry not to be more helpful.

brits said...
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brits said...
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John Cowan said...

Brits: There is no reason to think otherwise. Your father had only an O to give you, your mother had an A or a B, and gave you a B: that makes you a B. Both your parents had a + or a - to give you. Your siblings got either two +s or a + and a -, you happened to get two -s (as happens one time in four, on average).

manu said...

my mom is O+ n ma dad is A+...my group is A-...is this possible?

John Cowan said...

Manu: Sure. Your mother had only an O to give you, but your father had at least one A, so you are A. Both of your parents must have a + and a - gene, and by chance (one out of four) you got a - from both of them.

shagoon said...

Both my parents are B+, but somehow I happen to be B-. Is this possible????

John Cowan said...

Shagoon: Perfectly possible. Your parents must have had one + and one - gene to give you, and you happened to get both - genes, making you -. They also had either a B and an O or two B genes to give you, and you wound up with either one or two B genes, making you a B.

rcm said...

Is it possible to have a blood group of O-ve if the parents have both A +ve

rcm said...

How can a child have O negative blood if his parents have both A positive blood .Clarify with chart

John Cowan said...

rcm: Yes, of course. If both parents are AO (which comes out A) and +- (which comes out +), then if they happen to both pass 0 and - to their child, the child will be O-. There is only 1 chance in 16 of that happening, but less likely things happen every day.

manay singh said...

if a husband has AB+ blood group and a wife has o+ blood group.what will be the blood group of the child......??????

John Cowan said...

Manay: It could be anything except AB+ or AB-.

martina brawley said...

my parents are both a positive I am a negative rh factor neither parents have the rh gene, my 2 sisters and my brothers all have a postive and no rh gene is my parents related to me.

martina brawley said...

my parents,brother and 2 sisters are all A positive with no rh factor. I am a negative with rh factor am i related.

John Cowan said...

Martina: There is no reason to think you are not related. Positive parents can have negative children. (It's not possible for negative parents to have a positive child, however.)

jhon rich said...

i am O+ve and my husband is B+ve but our child is A+ve i am sure my son belongs to my husband. any other reason do you know?

jhon rich said...

my blood group is O+ve and my husband group is B+ve but my son is A+ve. i am sure that my son belongs to my husband any other reason you know?

John Cowan said...

Jhon Rich: There's something wrong with that story somewhere. Neither you nor your husband has an A to give your son.

jhon rich said...

That was lab mistake.. his blood group is B+ve

Saturnian_216 said...

#Anonymous22, it is possible for two (seemingly) Rh- parents to have an Rh+ child. One parent might actually be Rh+, but has this thing called weak D, in which the Rh antigen is too weak to be detected by blood tests, giving the appearance that he/she is Rh- when he/she in reality is Rh+. So that means that whichever parent it is could have passed on the Rh+ gene, thus producing an Rh+ child.

Saturnian_216 said...
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Saturnian_216 said...
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OJT Mom said...

My understanding in the article was that the Hh could disguise an AB but your later comments state that a type AB+ and O+ could not ever produce type O+ children. My problem is that is what has happened in our family. I can absolutely attest that my husband is the only possible father since I was totally chaste before marriage and faithful to him since. But our children twins and a singleton, are all type O+. My husband is not perturbed by it, but it bothers me to no end. I have read of a few ways this is possible although very rare. My husband frequently gives blood and I have occasionally given blood. My babies were typed at birth and I think before they were born, but I'm not posotive about that.

Amy McDonald said...

Hi,
I recently had a baby and we are having a great deal of trouble with jaundice which the pediatrician has attributed to the fact that she has "AB+ proteins" but her blood type is A+. I am O- and my husband is unsure of his, but assuming his is of course either A or AB +/- since baby is A and I am O. What I do not understand is how the baby came to have AB+ proteins if her blood type is A-?? I had no problems during the pregnancy other than some extreme (more than normal pregnancy) swelling around 36wks, she was born nearly 38wks. I had rhogam injections. I did have a miscarriage early first trimester about a year before this pregnancy, no other health problems, never had a blood transfusion or anything to get any antibodies or anything. Any insight would be greatly appreciated! Thank you!

John Cowan said...

Amy, I can't explain that, except to suppose that your husband is AB and that somehow a little B leaked in somewhere.

Amy McDonald said...

Thanks John, That was the only remote thing I could come up with but didn't see how it would be possible coming from him. It would seem more feasible to me if I were the one with AB and some of my blood that crossed the placenta got into her marrow somehow. For it to be from him it would have to be some rare genetic mix of passing on both A and B as well as some + since the protein is AB+ and her blood type is A-. But having had grad level immuno and genetics, I really just can't wrap my head around it and the pediatrician just says "it is too complicated to explain" which makes me think he doesn't know either. I appreciate the feedback! I'll keep digging!!

John Cowan said...

grad level immuno and genetics

You're way ahead of me, then. All I can do is a bit of combinatorics.

confused said...

I was wondering can a mom who is b pos and a father who is o neg have a child who is a neg with the rh factor???

John Cowan said...

Confused: Yes. The only impossible case for Rh blood types is two negative parents having a positive child. All other cases are possible.

Jezzabel said...
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