If my blood group is A positive, what are the likehood that both of my parents?
Well I pretty much answered this in one of your other questions. Most of the answerers here are right: the children of 2 O parents may be expected to be O. A children need at least 1 parent to be either A or AB. I notice you’re asking in another question about a sibling being A- with 2 O parents. In neither question do you mention whether they’re O+ or O-, but it doesn’t matter much unless they’re both negative (unlikely) in which case they would be unlikely to have positive children. (Negative children from 2 positives isn’t as weird.) Neither or you could have come from 2 O parents. It seems unlikely that it’s a coincidence you both have impossible types. The short answer is that this needs some sort of special explanation if they are both your parents. The most likely explanation is a mistyping (not that that’s common). I mentioned previously that some sub-types of A occasionally mistype as O:
