Most of us have heard of married people with kids suddenly "coming out" as gay to their families. It seems strange and counter-intuitive that they would have invested so much of their time and energy on a relationship that would have never worked out, and that they would have brought children into that situation. But something drove them on. Of course, aside from severe legal or social action in places where homophobia is widespread, most people in the above situation would be faced with others perceiving them differently.
When the environment communicates to you that a heterosexual married life and children is the best bet, then what is it a best bet for? Presumably, the widespread fear that humans will go extinct otherwise, or that that's what nature or "God" wants us to do. And of course, if we upset either, they will come and get us.
Yet, humans are overpopulating the Earth, and there is no sign that anything will wipe us out. If anything would, surely the way to prevent it is to become an astronomer, colonise Europa (Jupiter's moon) and avoid the imminent death of planet Earth. Presumably. These are all assumptions upon which best bets are placed. And the key point is that assumptions differ by culture.
So of course when the assumption is that humans will be wiped out by gays (as impossible as it may sound), the best bet is thought to be marriage and children. This drove our imaginary gay person to keep at it with their relationship and family.
What made them come out? Either:
1. the assumptions in the environment changed, e.g. a change of attitude in people, or
2. the environment itself changed, where the assumptions are different, e.g. gay marriage legal in certain places
3. the person created their own separate environment isolated from the external one.
Due to the popularity of an old post, The evolution of the human body, I have thought of creating a series called Top2Toe in which the human body is analysed in detail, taking into consideration all things like fingers, nails, arms, eyes, hair, skin... and everything in between. So check back later and don't forget to subscribe.