I'm pretty much with Dakota on this one... particularly as it comes to all of us need to be careful not to place ourselves in a place of overmuch temptation.

The only thing I'd add is a note on self-control.
How much we trust ourself is farily dependant on how much self-control we judge ourselves in having.

If you believe that a certian thing is right or wrong that belief alone will not determine if you'll do it or avoid it. Paul teaches in Romans 7 that the things we want to do we don't do and the things we don't want to do we do because of the sin that lives in us.

Therefore the issue is not what do you believe but what will you do in any given situation of oppertunity. If you are pretty sure that your actions will betray your beliefs then it's best to avoid that situation.

The only relevance of "If you have acted out sexually with a boy in the past" thing has, in my thinking, is that it may help you measure how far you are prepared to go in a given situation. Were as those who haven't may not find out till they get faced with oportunity.

Blessings
Cat.