Anything that is even slightly hereditary looks "largely hereditary" in the absence of environmental factors. That doesn't mean that large changes in environmental conditions cannot have a large effect on hereditary traits.
Body height is largely hereditary if you can avoid malnutrition. But improved nutrition has led to an increase in average height over time.
It's not improbable that spending ten hours a day indoors to study could have an effect on myopia in children, even if the variation among children who all study for approximately the same duration appears to be explainable by hereditary factors.
> Body height is largely hereditary if you can avoid malnutrition. But improved nutrition has led to an increase in average height over time.
To be clear, good environment increases the phenotypical expression of genotype. A malnourished population will have lower height variance than a well-fed one ceteris paribus.
Do you have a reference for that? The variance of most traits will increase as the variance and volatility of the environment increases. My guess is that the variance in stature in countries like Holland and Sweden has actually decreased significantly over the last 100 years. Military recruitment records would be the place to start looking.
But I honestly do not know the answer. Perhaps I should ask an LLM. But this might be a goid place to start instead.
Body height is largely hereditary if you can avoid malnutrition. But improved nutrition has led to an increase in average height over time.
It's not improbable that spending ten hours a day indoors to study could have an effect on myopia in children, even if the variation among children who all study for approximately the same duration appears to be explainable by hereditary factors.