It seems like a young age to be sure of your sexuality. Hell even at that age I probably wasn't even sure I was a heterosexual.
In any case when this girl was in the 8th grade (It is possible she was 14 at the time, many 8th graders are 13 though), she was not allowed to go to gym class because of her sexual orientation made the other students uncomfortable.
And in my quest to provide silly polls, I shall think of one...
... edit: The poll centers around lesbians since girls mature faster than boys and it wouldn't be right to lump them together at that age.