"The only way you can estimate environmental influences is by measuring them."

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There is no gene "for" such unambiguous bits of morphology as your left kneecap or your fingernail. [...] Hundreds of genes contribute to the building of most body parts and their action is channeled through a kaleidoscopic series of environmental influences: embryonic and postnatal, internal and external. Parts are not translated genes, and selection doesn't even work directly on parts.

— Stephen Jay Gould