@pacificae@SonicHyper please review grade school biology, or use the calculator here, it's entirely possible: http://www.biology.arizona.edu/human_bio/problem_sets/blood_types/inherited.html
don't forget dominant/recessive alleles
@SonicHyper sorry about my tone, I've gotten pretty annoyed with people coming in and going "NTR?!?!?!?!" on what is clearly a slice-of-life fluff piece
@haibane bro I get you I even hate NTR the most and when people starts making good wholesome romance NTR it makes me go Berserk... You showed a good example with that calculation page... so thanks for that I hope that that other dude understands THAT THIS IS WHOLESOME ROMANCE NOT NTR SHIT!!!😇
If the mom has the bloodtype AO, the O is silent, and the father has BO, again the O is silent, then using Mendelian genetics there is a 0.25 chance that the child has bloodtype OO.