Expert: Simone Flight - 5/3/2005

Question
If the mother and child are both blood type 0, what blood type can the father NOT be? I thought 0 and AB were universal. I'm thinking the father cannot be "A". Could you please explain? thank you.

Answer
Hi,
A child inherits one of the blood group genes from each parent.
If a person is classed type 'A' then there genes could be AO or AA.  An 'O' type has the genes OO.  Therefore a child that is 'O' and has an 'O' type mother -
i.e. they are both OO, can have a father that is O (OO), A (AO) or B (BO) but not AB.  If the father is AB then the child will be either AO or BO i.e. type 'A' or 'B'
This is explaination is clear when you look at inheritance using a punnet square.
There is a lot of information on this topic on the internet .
Hope this helps.
Simone