Confused by blood groups and parentage

[Sziasztok]

I’ve been clearing out my parents’ stuff after they died and found my Dad’s blood donor card. He was AB- and my Mum was O+. I’m O+ like my Mum. I remember him being this relatively rare blood group, when he was in hospital and the nurse talking to him about it. I did a bit of googling, and it looks as if an AB and O parent can’t produce a child that is O - I would have to be A or B.

There is no doubt that he was my Dad. I look very much like him, and inherited his dark brown eyes and olive skin. So I’m a bit confused to read the above. Are there any possible exceptions or explanations as to why I might have the blood group that I do?

If you are correct about all the blood groups then as far as I know the only explanation is that your Dad is not your biological parent. Maybe he was infertile and they used a sperm donor that looked like him or your Mum had an affair with a man that was similar in appearance. You inherit one allele from each parent and O is recessive so unless both parents are O type you won’t be.

@SarahMused If O is recessive her dad could have carried it and passed on to her? In the same way two brown eyed parents can produce a blue eyed child if they both carry the recessive gene. I’m no
expert though

As far as I know that is correct, this is what I learnt for GCSE biology so maybe science has advanced.

You can only be A or B.

https://www.thetech.org/ask-a-geneticist/articles/2011/ask427/#:~:text=An%20AB%20parent%20can%20indeed,Type%20A%20or%20Type%20B.

Apparently it can happen! You learn something every day.

Are you absolutely sure about your blood group?

I spent my life believing I was O pos like my mum. She was convinced of it too.

But when I checked my blood donor information it says A positive. Took me til 40 to know that.

No because you inherit one from each parent - her dad inherited A from one parent, and B from the other.

Her dad is AB, her mum is O (which in effect is OO). So she'll have inherited O from her mum and either A or B from her dad. Making her either A or B (because if you have genes AO or BO, your blood type is A or B respectively).

I think.

No.

The antigens are A, B, and O and your genotypes will be

AA or AO - type A

BB or BO - type B

AB - type AB

OO - type O

A&B are co dominant so if present with O your type will be A or B and present together AB. To be O you need two O genes.

OP’s mum was therefore OO to have an O phenotype and her dad AB therefore OP could only be AO or BO (inheriting one gene from each parent)

OP - make sure you have proper records of your parents’ blood types before panicking.

Ooooh! This is interesting - things have moved on!

Don’t panic too much - it’s not quite as simple as we learnt at school. I had a panic when I first when to blood donors as I was O negative. My parents are both O positive. It was back in the day before google and bless him my dad spent all day on the phone trying to get an explanation for me. Basically he was told it’s all much more complicated than we learn at school.

That’s different though - both parents being O could ONLY have an O child and the rhesus +/- isn’t inherited in quite the same way so perfectly possible to have a - child if parents are positive.

I think if you have a different ethnicity in your background/ genes, in particular north East Asian, then it is very rare but not unheard of…however if you are white then it would probably be highly unusual . I do have a family member where the relevant parental blood groups do not appear to match the child’s blood group but child does look like father so I presume there may be a blood type mistake somewhere, people do get their blood type wrong.

I gotcha. Thanks for explaining, been a long time since I did genetics!

out of interest, I’m A- and DH is B+ - what would you say would be the options for our DC? If I’ve understood right they could be anything!

You are either AA or AO and your DH is BB or BO

Therefore possible genotypes are

AB, AO, BO or OO

so effectively any of the ABO blood groups are possible.

@Coatscoatscoast

Also a while since I studied but we have some unusual haemoglobinopathies in my family so it’s an area of interest.

Thank you everyone. My Mum was definitely O+, from her blood donors records. I know I’m O+ because I needed to have my blood tested for work. It looks like it may not be straightforward. I know virtually nothing about my Dad’s side of the family, but do have a second cousin, so will pick her brains. My Dad could easily have passed for Southern European or Middle Eastern, but as far as he knew, his family came from Sussex for generations.

@Sziasztok

My son has a Hb type that is associated with people of Afro-Caribbean descent. I do too - my mum was West Indian so not unexpected.

Except my son looks white with blue eyes and blond hair - literally looks completely white.

If he had kids he could pass it along and there’s the potential a completely ‘white’ for generations kid could have an Hb type that confuses medical professionals.

Both my parents are O-. So am I.

My ds is A-.

Think his dad was A+? He was definitely A and the also had AB- in the family.

I remember having to have some type of injection because of our blood groups when he was born.

Very interesting links here though. Everyday is a school day!