Bieran De Saille asked:
If I have B+ blood and so does my wife how can our son have O+ blood?
Kat - Well, youíll be asking the milkman what sort of blood group they have! No, this is all very simply explained. Blood group is determined by a set of genes. You get one gene each from your mum and one from your dad. Blood groupís determined by basically two different genes called A or B. You have certain versions of these and you can also get a version called O. These genes make proteins on the surface of your blood cells so if you have a gene that is A you make A proteins and they on the surface of your blood cells. If you have a gene for B that makes B proteins that go on the surface of your blood cells. If you have O then you donít make any proteins. Going back to what I said about you having one gene from your mum, one from gene from your dad - if you had one B gene and one O gene your blood group would be B because youíve still got a gene thatís making B proteins. Your blood cells are B. If you then were with someone else who had one B and one O and you had a baby with them your babies could either have BB genes, their blood group would definitely be B; they could be BO because theyíve one gene from you and maybe an O gene from mum or dad or they could have the two Os, in which case they would be blood group O. Itís perfectly possible to have two B parents having an O child from which you can actually infer both of you must be BO.
Chris - Thatís because group O is recessive.
Kat - Exactly, group O is recessive because you have no proteins on the surface of your blood cells from this group. If you have even just one A or B gene that determines your blood type.
Biren Desai asked the Naked Scientists: I have B+ Blood and my wife has also B+ group. But I wonder my son has O positive group, How? What do you think? Biren Desai, Sat, 21st Jun 2008
Don't file for divorce Biren...
Each of you will have two genes for ABO grouping. O genes don't express a protein, A and B express the A and B proteins respectively.
Here is a list of the prevalence of various blood types around the world.