I'm a straight female adult... but the age thing rings true no matter what gender/orentation, so I'm gonna comment... From experience.
It is completely possible for a person to fall for someone much older or much younger. I think both parties have an obligation to themselves to wait (if the younger party isn't legal that's where you hit the really grey area) and see if there really is something there or it's just an attraction... Im a firm believer in building a strong friendship first and then going from there. If you're unable to sustain a friendship with the other person, then the reality of a relationship is really just a pipe dream on your part.
A lot of you have said someone younger is like dating a child and someone older is like dating a parent... I truly believe it depends on the individuals involved. I felt the exact same way until I was in that position myself. I'll share a short (generalized) story... When I was 17 I met, and completely fell for a man 25 years my senior. I had no idea of his age when we met (nor did he have any idea of mine), but we hit it off, became friends and I wrote my feelings off as a silly crush. Years later (when I was already a legal adult) I found out he had a thing for me as well and we attempted a relationship. For many reasons, it didn't work -- not because we didn't want it to, but moreso because of many outside influences..... To this day we have an amazingly strong friendship and I can honestly say he's one of my best friends. People look at me like Im crazy when I say that but it is true.
I used to think we should have attempted a relationship earlier on in the time we knew each other but I now realize it would have been absurd. I would have been hurt, we would have lost the friendship and I'd probably be bitter about the entire thing.
In any event, I guess what Im saying is if this guy really feels something for you, he'll be willing to wait till you're a little older... if not, then you know you're just a notch on the bedpost. If that's all you're looking for, go for it, but I do not recommend it in the slightest.
"You're every gay man's wet dream!" ~ MA
If in Heaven you don't excel, you can always party down in hell...