Homosexuality and Natural Selection.

I actually heard a study done where large families including a long line of brothers would be more likely have the youngest brother be homosexual, having something to do with the conditions in the womb. but it also goes into your statement about homosexual family members being geneticly put inplace to tend to the children of other family members. it seems to fit and is also seen in nature where you have certain females not taking a mate but instead tending to the young of the whole collective.
just complimenting your point!