Question about blood types and parentage.

[Coral Rhedd]

A few years back, when my grandmother was still alive, she and her three daughters went to the local health fair. At the fair they were able to get their blood pressure checked and be screened for diabetes.

 

One test they availed themselves of was a blood typing test. It turned out that my mother and my grandmother shared the same blood type, B. My two aunts were O and A repectively. My grandfather has been long dead and there is no possibility of now knowing his blood type. My mother always wondered if the outcome of this test meant that one of her sisters was not a true biological sister. (There were rumors that the middle sister was adopted.)

 

I know nothing of blood typing. I am wondering if these different blood types among three sisters tell a story -- or are my Mom and I just being paranoid?

[Babbler]

My grandfather has been long dead and there is no possibility of now knowing his blood type.

 

Well, I thing you could exsume him and look for some kind of remains of blood. But I am sure your not THAT curious.

 

In any case, I looked up and it seems you would need the blood types of both parents' blood types to test parentage with blood types.

 

http://www.bloodbook.com/inherited.html

 

Of course, I am not a doctor or even a medical student; I am just a college student, sho I would go seeking more expertly opinions before I would do anything.

[Coral Rhedd]

Thanks. The link you referenced makes it clear that it is possible for siblings to have three or even four different blood types among them.

[Nave]

yea if u had ur grandfathers blood type you could do a punetts(dunno how to spell) squre from bio and figure out what bloodtypes are produced. And just because she dosent have the same blood type dosent mean shes not a relative. For example i have O- and i think both my parents have some sort of b and same with my sister.. Could u maybe check his bithcertificate possibly because sometimes they have blood types on there and also check any medical records?

[Coral Rhedd]

My grandfather died in 1947. There is not record of his blood type that I know of. However, we have enough family scandals to keep me busy for years. Just researching the family tree is proving to be a great revelation.

[ecoli]

your best bet is genetic testing. There are certain intron genes that are used as genetic markers within the family. Even without the father, it's possible to tell. Of course it may be better, psycologically, for your aunt never to find out the truth (if she's adopted)

[schlieffen]

Actually, its quite possible...

 

Its a case of multiple alleles (you can find this in any 1st year Biology textbook). It works pretty much the same as dominant/resessive genes, except there are a few more possibilites. You have I(A), I(B), and i. If you have type A blood, you could either be I(A)I(A) or I(A)i, same for type B. If you're type AB, then you have I(A)I(B), and if you're an O, you have ii

 

Now, in order for you to have aunts that are type O and type A blood, and for your mother to have type B blood, your grandmother must have had I(B)i, and your grandfather I(A)i. Now if you work out the punnet square, you get 4 different possibilities, I(A)I(B), I(A)i, I(B)i, or ii; type AB, A, B, or O.

 

So assuming your grandfather was I(A)i, then your family's blood types work out just fine (as any blood type is possible for your grandparents' children), and your aunt likely wasn't adopted. Hope this helps!

[ecoli]

But they can't test their grandfather, so they can't assume he was bloodtype I(A)i. If Coral Rehdd's aunts aren't related by blood then his/her grandfather may not be I(A)i.

[schlieffen]

But they can't test their grandfather, so they can't assume he was bloodtype I(A)i. If Coral Rehdd's aunts aren't related by blood then his/her grandfather may not be I(A)i.

 

I know, all I said was that its possible.

[ecoli]

Oh, in that case it makes sense.