alt Hacker News > Almost all human traits are partly genetic and partly due to the environment and/or random. If you could change the world and reduce the amount of randomness, then of course heritability would go up.
It implies that the only environment that matters is either purely random (truly random accidents, circumstances) or non-systematic (results from non-linear interaction of environment and genes).
When stated that way it almost feels like a tautology because this is what genes exist to do in the first place. To control the interactions of their vessel and environment to the maximum degree. And from the perspective of an individual gene, all the other genes are part of the environment too.
> There is no such thing as “true” heritability, independent of the contingent facts of our world.
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The point is not that it is something hard to compute that we can only approximate. The point is that there is no well-defined heritability independent of the environmental distribution.
> while it's easy to do harm (lead exposure) it's all but impossible to do any good.
That's just a meaningless statement no different from "while it's easy to subtract negative numbers, it's all but impossible to add positive numbers."
> or non-systematic (results from non-linear interaction of environment and genes).
Non-linear interaction does not mean non-systematic. Computer programs are fully deterministic (and therefore "systematic") while being non-linear (and therefore generally unpredictable). It is true to say that when things are non-linear it's hard to tell with certainty what effect some policy will have, but given that most human systems are non-linear, this is true for just about everything.
This is demonstrably untrue. IQ has increased consistently for decades, far faster than genetic factors can explain. Environmental factors like education, nutrition, and medical care are the obvious explanation.
What you're saying is completely accurate, but I'd add that it's all relative. Are you falling towards the ground, or is the ground falling towards you? For instance malnutrition lowers IQ, in both directions. There is an inverse correlation between IQ and BMI, but what's most interesting is that that correlation has maintained just as strong even as obesity rates skyrocketed, which is suggestive that there's probably something causal, in some direction, somewhere in there.
And so in modern times if it turns out that eating less than most people apparently want to contributes to IQ, are you doing something good by eating less, or are they doing something bad by eating more? I think it's basically the same thing, just looked at in different ways.