I have know several couples who are lesbians, who are in a long term relationship, and who are raising children together. In each case those parents are highly committed and have done a very good job with their kids.

Yes, a large portion of teenagers who commit suicide are either homosexual or bisexual. Often that's because the thought of facing a lifetime of bigotry is daunting, because they can't cope with the reaction of peers (humilation, ostracism) and because its all too much. When are we going to have a world where people can grow up feeling that they don't have to fit an image provided by someone else. I made sure my children knew when they reached their early teens that if they were gay or bisexual, it wouldn't affect the way that I love them in any way.

As for following nature, some species of ape are bisexual.

http://www.primates.com/bonobos/bonobo-info.html

http://www.primates.com/chimps/chimpanzee-info.html