Your first question...

...is ridiculous, because we don't know any more or any less about our attractions than you or anyone else. I'd even love to hear your answer to "Why are you attracted to men/women" because the answer can't possibly be a whole lot different than any answer we'd give. Why is a homosexual man attracted to other men? Why is a necrophile attracted to dead bodies? Why am I attracted to LGs, or you to men/women? The answer is the same

Also, I am also attracted to women and LBs. I'm a straight teleiophile and a bi pedo. Guess what it has in common is that they're all (living) human beings. *hint, hint*

Now, as to what should be allowed or not...too long to answer in detail. Let's just say that the insane amounts of sexual repression that happen today are definitely bad

Someone should go to jail if they cause someone some kind of HARM, and you can't say that minors having sex play with each other or with adults is inherently harmful because in other societies (in time and in space) this isn't even an issue

Gah, I'm just gonna stop here before I go on an enormous rant ><