[Snargorf]

You don't even need to look that hard.

Poor eyesight has no adaptive benefit. Yet many, many people need glasses. I guess it's just 'difficult' for our genes to grow a sharp eye focusing system, so they often get it wrong.

The same may be true of homosexuality. So even if there's nothing adaptive about being gay, it keeps happening because sexual tuning in the brain is a hard target to hit.

Homophobia may be an adaptation to this. It makes parents force their children to act straight even if they're gay.

[gwern]

> Poor eyesight has no adaptive benefit. Yet many, many people need glasses.

Many people... in particular industrializing countries. Our genes have a great sharp eye focusing system. You won't find much myopia in a random tribe.