What Causes Homosexuality?

[Squilliam]

xxbrothawizxx63 said:

Squilliam said:
Overpopulation. It is an environmental factor where human beings are exposed to an environment which is 1000's of times greater population density than for the majority of human history.

The other major factor is genetic from the female side, I.E. an increased rate of fertility at the expense of producing gay sons.

Though I don't see how overpopulation is a real factor unless you said it in relation to your next point there is some substance and data to suggest that there is truth in your second point. 

Several studies have found that the the gay child in a family typically is the last or near the last. Supposedly, the male fetus is seem as somewhat of a foreign object in the womb and and a women's body naturally tries to "feminize" the fetus. The hypothesis states that as a women has more sons, here body become more adept at this process resulting in homsexual sons. That doesn't explain lesbians though.

A family with a lot of sons is also a family with crowded living arrangements. People are affected by their environment long before they are born. It doesn't disprove the population connection because you can also explain the sons argument with density.