[thaumasiotes]

> Mine is genetic.

> I have very simil[a]r values than my mother.

Well, everything is genetic. The amount of sunlight you're exposed to is no less a genetic effect than how tall you grow to be. Without genes, you wouldn't have any behaviors or phenotypes at all.

So the interesting question is not "is this phenomenon genetic?", because the answer to that is always "yes". The interesting question is "what can influence this phenomenon?". In this case, we already know that (1) within a given culture, genetics are a strong predictor for myopia; and (2) once you do a cross-cultural comparison, the effect of culture absolutely overwhelms genetic measurements. Most people who become nearsighted in modern cultures would never become nearsighted in premodern cultures.

[throwaway202022]

This is 100% true. Genetic predisposition to something != inevitability.

[thaumasiotes]

> Genetic predisposition to something != inevitability.

That depends on the thing. Whether you grow five or six fingers on your hands is determined by your genes without much reference to anything else. Whether you reach a "natural" height or develop stunted by malnutrition is also determined by your genes. It is more responsive to environmental conditions than the number of fingers on your hand is - but that responsiveness is determined by your genes.

[tchvil]

My wife is -3 myopic, I'm -6 from childhood. And our 3 kids of 19, 17 and 10, have all a perfect sight.

They went outside often but nothing extreme. We have big luminous windows. And they spend a fair amount of time on screens too.

It can be so multifactorial, I have no idea why this luck. As I was convinced they would all wear glasses.

[jamal-kumar]

All of my immediate family members need glasses but me, which is pretty interesting.