Quote Originally Posted by Eric C. View Post
All of your questions are easily resolved if we assume that,

a) Family in legal terms is represented by a couple of two, of the age of consent or higher.
b) The sexual orientation of anyone (either gay or straight) is what they're born with, with no possibility to ever change it.

A lot of social and biological studies conclude a) to be the optimal pick, and prove b) correct.
I think both assumptions are arbitrary and alas can't serve a basis to anything, really. With respect to A, if more than two persons of the age of consent want to be a familty, what makes you rule them out in such conclusive manner? With respect to B, please have a look at Bisexuality - Wikipedia, the free encyclopedia to widen your horizonts a bit.