Well, if I were to give a theory:
girls are less into reptiles, they are more of a 'guy' thing (like cars and stereos and whathaveyou). Those who are interested in them usually dabble when they introduced by a boyfriend (hence the lack of single girls) or perhaps when they are settled down and think 'hey, I always wanted to see what it would be like to keep a snake!'.
Guys, on the other hand, seem to think it's 'cool' to keep herps (not all of them of course but a lot of the passers through just pick up a ball python to impress their buddies). Hence the abundance of young single male herpers.
All this notwithstanding, I am a young female herper so I guess I just partly nullified what I said :P