[tptacek]

You're saying "60-80% heritable" as if that meant something. But you're also wrong: not only do separated twins raised in different SES settings have differing IQ results, but the heritability of IQ itself (whatever its cause) is also SES-dependant.

[l0t0b0r0s]

recent studies showing heritability for IQ as high as 80%.[8] IQ goes from being weakly correlated with genetics for children, to being strongly correlated with genetics for late teens and adults."

Bouchard, Thomas J. (7 August 2013). "The Wilson Effect: The Increase in Heritability of IQ With Age"

[tptacek]

This doesn't respond to what I just said. Heritability is not evidence of genetic determinism. It makes sense that age would amplify both any extant genetic influences on intelligence, and any gene-environment interactions, while minimizing shared environment facts. The basic idea of "heritability" isn't in question; the genetic determination and fixity of intelligence is.

[l0t0b0r0s]

Heritability is genetic determinism. It's not like you get a different set of genes as you age. Are you indirectly saying that the genes responsible for physical characteristics follow different rules than the genes responsible for intelligence? Like could your environmental factors change your height? I would say maybe it is something in the middle like the genes determine your maximum potential in physical and mental expression.

[tptacek]

No, it very obviously is not. This isn't something we need to argue; you can simply go look it up. The number of fingers on your hands: not very heritable. Whether you wear lipstick: very heritable.

You can set your watch to people on message boards making arguments about the genetic determination of intelligence that rely almost entirely on heritability statistics. It seems pretty clearly to be a cargo culting phenomenon; how else could you have very specific heritability numbers without even knowing what the term means? I'm curious where you got it from.

[l0t0b0r0s]

Polydactyly is a condition in which a baby is born with one or more extra fingers. It is a common condition that often runs in families.

Is this not what heritability means?

[dan-robertson]

Heritability means that parents having a trait explains, in a statistical sense, some amount of how much a randomly chosen person has a trait. So some of heritability is genetics and some is the shared environment.

For example, someone is quite likely to speak the same first language as their parents, and for this reason, the statistics for heritability come up with a high number for how heritable a trait first language is. But this isn’t because of some English-speaking gene, it’s because lots of environmental conditions are common between parents and children.

The intuitive reason that the number of fingers on your hand is not heritable is because lots of the variation comes from injuries which are not explained very much by whether one’s parents lost fingers from injury. Genetic causes for an unusual number of fingers are much less common than accidents and so can’t cause much of the variation that is observed across a population.

Because it is quite reasonable to get a high heritability number for something that is not genetically determined (and a low number for something that is), one cannot really argue anything about genetic determinism from heritability numbers.

[sethev]

You cited this reference up thread: "The Wilson Effect: The Increase in Heritability of IQ With Age". It should give you pause for your definition of heritability that this paper is saying it changes with age. As you point out a couple of comments later, genes don't change with age.

If you're going to cite heritability numbers, you have to use the technical definition of heritability (which is what these papers are using).

> Is this not what heritability means?

No, not at all.

[11235813213455]

No, heritability is a lot due to the fact the parent will educate, spend time with his child, it's no longer about genes.

Are there enough studies with adoptions? Because this would show exactly what we mean about genetics