Along with Trowa's age, another thing that has popped up is his blood type. Where that came from is also past my knowledge. It is said that he is AB on some web pages. Usually there is note that he is a "perfect" fit for the AB blood typology. Perhaps it is his blood type, I mean if anything his blood type, if brought up and checked through tests will undeniably be A, B, AB or O. I just have yet to know when his, as well as the other pilots', blood type came up for absolute proof.