Is blood type O possible with A and B parent?

Blood type O is possible with A and B parents if both parents are heterozygous for their blood type. This means that both parents must carry one A allele and one B allele, in addition to the O allele. When two such parents mate, there is a 1 in 4 chance that their child will inherit two O alleles and have blood type O.

Here's a breakdown of the possible blood types of offspring when both parents are heterozygous for blood types A and B:

- A: 1 in 4 chance

- B: 1 in 4 chance

- AB: 1 in 4 chance

- O: 1 in 4 chance

Therefore, it is possible for a child to have blood type O even if both parents have A and B blood types.