[He tenses at the question - of course it's personal, but not necessarily too much so and Inara's so nice about it. It's not something he wants to talk about but at the same time it doesn't feel right not to - not with his intentions in coming here. Not after practically saying he has trouble connecting with others.]
No, no... it's fine. [A pause as he shifts, suddenly unsure of what he should say.] I suppose it's just one of those things that have always been there..? I, uh... I've always been a lot younger than my peers. A lot younger. It doesn't exactly make it easy to fit in.
[Only one of many reasons, but it's the one he feels more comfortable offering.]