Am I really not "built" for certain martial arts?

So I'm looking for a new martial art to try out, I've been off of kungfu for a while now (that and dancing for 12 years, thats my athletic resume). I quit due to a slight knee injury, and...well I just didn't go back. I have friends there, my step-father goes there and the teacher is great and all..but. Its more of a kungfu fight club than a school and I just couldn't find
myself there, I felt no structure. I just learned a little of this and a little of that, no particular style. Recently, i found a MMA gym in the local area and I might just try it out. They got, MMA, wrestling, Brazilian Jiu-jitsu and Muay Thai. I have to say that my overall opinion of MMA has changed drastically. I always thought it was thuggish and undisciplined....heh....I was way wrong. Now I'm very curious about it, in fact I'm very tempted to try out that Muay Thai class they have (if that doesn't work out then I'll hit up the MMA class then). The thing is my friends can't see me as a MMA fighter or a thai kickboxer at all. According to them I'm just not built for it (that and I guess I don't have the "personality" to learn Muay Thai, honestly what sense does that make?). They see me more as a kungfu person but I just don't know. I just don't like the fact that I can't do this or that just because my body is not structured that way. I'm 24 at 5'7" and 140(ish). I'm wiry but I'm very lean, more a dancer build than anything. My legs definitely are my strength, I don't have much up top but I believe anything about me can change and my body will adapt to whatever need arises so i guess that's why I disagree with that comment. Should I give it a shot, or am I seriously not built for something like that?