Everyone has missed what is so obvious. I think your mom has some explaining to do to her husband and maybe she can help you find your real dad while shes at it. sucks to be you!

i agree with #219.

they got some 'splainin to do =P

Everyone is putting too much faith in high school science. Ask your doctor or a biology professor. Blood types are a lot more complicated than A, B, and i/O. There are also contributing genetic factors with other proteins. My freshman year of college, I learned when donating blood that I am A+, while both of my parents are O. I approached my professor, who explained to me that these contributing proteins are what bond the A or the B to your blood cells. It's not A, it's i^A, etc. So one of my parents is i^A,i^O or i^A,i^A, but lacks the bonding protein, while my other parent is legitimately i^O,i^O and has the bonding protein, thus I got the i^A from on parent and the i^O and the bonding protein from the other. Thus, here I am. Trust me, I know my dad is my dad because my parents were swingers (ew, I know) and there WAS a question of who my father was, but even if my parents hadn't gotten a paternity test (which they did), my dental records are almost identical with my father's (right down to a crooked tooth and a too tall tooth on my bottom teeth). So it IS possible that your parents are your real parents. Unfortunately it is also very possible that they aren't. Just give them the benefit of the doubt, or if you are really concerned, approach them. Talk to them about it. You don't even have to accuse them of anything, just say you know it's possible for them to be your parents, but that you interested in knowing if it's the simple explanation or a mutation, because a mutation would be important for you to know were you to ever need a transfusion. If you've discovered your blood type through donating blood, it is unlikely that they would take your blood if you have a significant mutation, and in such a case, they would notify you as you would be ineligible to donate again in the future (except maybe donating plasma).

Also, to be fair there are extremely small odds (incredibly extreme) that one of your parents is the mutant and not you. Such as a chimera. But don't count on it because that is so extremely rare that I only felt like throwing it out there for conspiracy theorists. There are cases where women have failed maternity tests (it's sometimes required for welfare cases) due to chimerism, despite having given birth to their child and never having had the children switched at birth.

As weird as it sound, it actually IS possible for that to happen. DNA has the ability to mutate, and so a child can have a different blood type than both of it's parents. I would know, I'm the AB- child of an A+ and O-. Here's a site that explains it a little better: http://www.thetech.org/genetics/ask.php?id=181 hope it helps!

You should have your test redone. Your sample could have been mixed up in the lab or the lab tech could have screwed up.

im not sure if anyone else said this but #19 is wrong. O is recessive.

none of those outcomes are that bad. apart from the mutant one

Amazing how many people here think they're experts on genetics because they've taken a high school biology class. I'm a senior biology major (who has taken higher level genetics) and this is absolutely possible. #217 has a wonderful explanation - and that is one of the circumstances where this could happen. I should add, though, that the Bombay phenotype is very VERY rare! It's much more likely that you're not your parents' son or daughter (Sorry!). Unless, ofcourse, there has been a history of the "h" recessive allele in your family and your grandparents are cousins (or related), making either your mother or father a recessive "hh" - thus leading to an apparent "O" bombay phenotype.