If your father has AB+ and your mother has O+, can you also have O+ as a blood group as a child?

Answer

Dear Anouk,

The blood group is determined by 2 genes that you inherit from your parents (one from each parent). There are 3 possible genes (A, B and O) that can occur in different combinations.

Blood group O means you are actually OO, so you have 2 O genes. Someone with blood group AB has an A gene and a B gene. Someone with blood group A can have either AO or AA as a gene composition, and someone with blood group B can have BO or BB. Each parent passes on 1 gene to their child, and the combination of the 2 parent genes gives the child’s blood group.

In the example you give, the father will pass on gene A or B, and the mother will pass on gene O. This means that the children will be either AO or BO, so they will have blood group A or B. A blood group O is not possible.

The + stands for the rhesus factor, which is inherited separately from the ABO blood group. One only says about a rhesus factor whether one has it (+) or not (-). With 2 parents who are Rh factor +, it is perfectly possible that their child is also +.