Not disagreeing with your original point, just adding that if you were controlling for environmental factors (everyone has equivalent environment), then you'd s

Not disagreeing with your original point, just adding that if you were controlling for environmental factors (everyone has equivalent environment), then you'd see more contribution to variance in phenotypes from genetics than environment. So for homosexuality, I'd bet the reason genetics don't contribute as much is because of the heterogeneous environmental conditions (just think about where you grow up and what religion you are for example). Edit: a good example of this in action is handedness, because different societies historically have different advantages to using different hands > Second, the samples used to estimate the handedness heritability were from different places, different years or different centuries and were not always representative of the general population. Heritability is not an intrinsic property of a trait: it varies with phenotypic and additive genetic variances and thus can vary across populations and across generations https://www.nature.com/articles/s41437-019-0274-3 https://www.nature.com/articles/s41437-019-0274-3