Not all but most very common obviously harmful mutations involve some kind of tradeoff or somehow fails to affect reproduction.
If something kills you in older age it’s free to spread, if something isn’t so terrible it can also spread through founder effects in a population but if some trait obviously hurts people at a young age but is still common it’s a good sign that it’s giving or did give some kind of advantage. .
Not all but most very common obviously harmful mutations involve some kind of tradeoff or somehow fails to affect reproduction.
If something kills you in older age it’s free to spread, if something isn’t so terrible it can also spread through founder effects in a population but if some trait obviously hurts people at a young age but is still common it’s a good sign that it’s giving or did give some kind of advantage. .
Is homosexuality very common, at 1-3%? This requires quantitative analysis.
1 in 30 of the population counts as very common in genetics terms.