It think it would be easier for a curious person to experiment with someone that has experience with that sex. I mean, a gay man with a straight or bi woman, a lesbian woman with a straight or bi man and so on.
I also think that homosexual people usually have less doubts about their sexuality when they are adults, because society encourage them to try to be straight. However, nobody tells heterosexual people: you may like your own sex, try it.
There is a dating service called "Bro" for meetings between straight men
RE: Boy looking for Boy and Girl looking for Girl