Blood types and parentage

[peanutter]

Ok, after watching Offspring last night, something has been brought to my mind again ...

I have a friend whose bloodtype is B, but their parents are O (mother) and A (father).

Conventional wisdom says that their dad actually cannot possibly be their biological father ... but they refuse to ask their mum about it ...

But I wasn't watching Offspring carefully at the end of the episode, so I'm unclear as to whether or not my friend's dad could actually be their dad ...

My friend was a homebirth, so the mum is definately the mum

Anyone know the answer?

I will of course respect my friend's decision not to pursue the matter, but I am really wanting to know ...

If nothing else, so that if they ever do decide to sind out, I can be available to support and answer Qs if and when they're ready to talk about it with someone other than mum and dad...

Anyone know?

[Ca Plane Pour Moi]

There are three "genes for" blood types: these are called A, B and O.

Back to senior science for a moment. Genes are normally dominant or recessive. For example, brown eyes is dominant to blue eyes - so you would have genes for (the genotype) brown and blue, but only brown would be expressed. The expressed gene is called the phenotype.

Blood is a bit different. O is recessive, but A and B are co-dominant: they are both dominant. So if your genotype is A and B, your phenotype would be AB.

To have phenotype blood group O, you'd need two recessive genes: genotype OO.
Group A could be AA or AO (as O is recessive), B could be BB or BO (yes, you can laugh at that one).

In short: to be blood group B with a group O biological mother, your biological father would have to be either B or AB as his blood group. Your friend would have the genotype BO.

[Jakabella]

WOW thats really interesting!!

[Jellybean29]

I'm A- and my DH is A+ and they said our DS is O!!!!

and i KNOW dh is the father!!!

[Ca Plane Pour Moi]

BBB - you and your DH are both genotype AO, giving your DS genotype OO. For two AO parents, there's a 3/4 chance of a baby being group A (AA or AO) and 1/4 chance of baby being group O.

Rhesus factor (+ or -) is coded for elsewhere, so that doesn't affect the blood group (Rh+ being dominant).

[Jellybean29]

BBB - you and your DH are both genotype AO, giving your DS genotype OO. For two AO parents, there's a 3/4 chance of a baby being group A (AA or AO) and 1/4 chance of baby being group O.

Rhesus factor (+ or -) is coded for elsewhere, so that doesn't affect the blood group (Rh+ being dominant).

thank god i thought ds was immaculately conceived for a while there!!

[Sammiejane]

I love explaining blood groups I even draw up the boxes to show how it works... Spewing that it has already been done so well
Very sad of me!!!!


Sent from my iPhone using Tapatalk

[Ca Plane Pour Moi]

Hehe thanks SammieJane. I love Punnett Squares too! And cross-breeding flies. I had a computer programme that let you do that many, many years ago.

[starangelk]

DH and I are both o+ and we found out that DD is o- and I freaked out wondering if that was possible. We only found this out as we did cord blood banking. Dr Google taught me this was totally fine but I found it all so interesting!

[onthefly]

I did not know all that, thanks!

[peanutter]

so basically, my friend cannot be their dad's biological daughter.

because the mum must be OO, and the dad must either be AA or AO.

so for my friend to be the child of those people, they would either be A or O.

not B.



is that correct?

[AnyDream]

Yes Peanutter that is correct.

But you would want to be 100% dead certain that the parents are reporting their blood types right. People tend to forget and say the wrong thing. This is the reason why, before you have major surgery, they take a sample of your blood and keep it at the pathology place - so that if you need a transfusion they can check the type so there are no mistakes.

[Jellybean29]

so basically, my friend cannot be their dad's biological daughter.

because the mum must be OO, and the dad must either be AA or AO.

so for my friend to be the child of those people, they would either be A or O.

not B.



is that correct?

eeps

[onthefly]

Maybe he's AB...?

[Kimbles01]

I'd be curious to know what the likelihood of someone having a rarer blood type and also being left handed is!! As less than 10% (as I understand) of the world's population is left handed, and around 3% of the Australian population have type AB blood - so I wonder how rare that makes me, being a lefty AB human?!

[Ca Plane Pour Moi]

Peanutter, yes. If the genotype was AB, then the dad would have blood type AB.

[Jellybean29]

I'd be curious to know what the likelihood of someone having a rarer blood type and also being left handed is!! As less than 10% (as I understand) of the world's population is left handed, and around 3% of the Australian population have type AB blood - so I wonder how rare that makes me, being a lefty AB human?!

maybe that person is the only one with the cure for a zombie apocalypse? we better find them!

[peanutter]

nope ... they're blood donors, and bloodtype is on their cards ...

but when I twigged ages ago (we're talking 10 years ago) and I said something, my friend basically said they wouldn't want to know ... and I'm completely going to respect that.

I don't understand it at all, I couldn't possibly leave that unaddressed, but it's not my life, my parents, my siblings or my potential unknown biological father ... there is no loving option for me other than to completely leave it unless and until they bring it up. Which might never happen.

But I would imagine that at some stage in their life they will want to address it, and as far as I'm aware, I (and their mum!) are the only people aware of the situation, so I will be ready and available.


but sad, sad panda with a heavy heart for my dear friend