It seems like core psychological traits like intelligence, personality, and psychopathology aren't very malleable, but secondary ones like skills, attitudes, beliefs, and values are. It's almost like the distinction between hardware and software.

Chuck, I didn't know multivariate analyses could check for rGE.. I thought they partitioned the variance between traits into the ACE model.. Could you link to a study were they check for rGE and don't find it?

Eduardo, They have a page up at cog-genomics.org

Doesn't the importance of relatedness also depend on how related you are to the average person you deal with? So relatedness would matter less in a highly inbred village? What is the expected level of altruism for close kin when the average person in your vicinity has cousin-level relatedness?

Great post.. I think part of the "nonshared environmental variation" is actually shared environmental variation that is ignored because of assumptions inherent in the behavioral genetic methods. See here for my discussion of this with regards to IQ: http://www.gnxp.com/blog/2009/11/does-family-matter-for-adult-iq.php

kjmtchl, We're on the same page that shared effects are relatively small in the middle class populations they sample for these studies. To get a bit deeper, assuming the shared environmental figures are insignificant as you say, why do you think natural selection would favor such a high degree of biological determinism? Wouldn't there be a selective advantage to organisms who psychologically adapt-- not just in beliefs/values, but also in emotional and cognitive abilities tendencies-- to the conditions they're raised in? Of course, too much malleability would be a liability because your psychological development would be at the whims of other individuals, as well as environmental flukes. But still, don't you think there would be a selective advantage to malleability beyond "give me the right biological inputs (nutrition, etc.) and I'll develop my genetically programmed personality"?

Correction to what I just wrote.. "nonshared environmental variation" should be "additive genetic variation". There is of course no assumption in the calculation of e^2 because its just 1 - rMZ. The reason this matters is, once you have significant shared environmental variation, systematic causes of the nonshared environmental variation (e.g. peer groups, status competition, etc.) become plausible.

By any non-supernatural definition, "free will" refers to behaviors that emanate directly from an individuals mind rather than external factors. Variation in the mind is a product solely of genes and environments, so we would expect free will to be influenced by both. To separate them from free will as Caplan does is a logical error.

It wouldn't be necessary to do so many heritability studies if psychologists and sociologists would stop operating under the assumption that their trait of interest is determined by the environment. Even when they say, like Kaufman, that genes matter, they don't take it fully into account in their hypothesis generation. The heritability research forces them to.

By the way, thanks for making this post. GNXP is the only intelligent blog for discussing behavior genetics and all its implications. Lately it hasn't had much on that particular subject so thanks for helping keep things rolling!

Jason, Even if heritability stayed the same from one generation, that wouldn't necessarily indicate intergenerational genetic transmission. That's because equally heritable but different causes may underly the trait for each generation. I would guess that there are some traits like g, work ethic, etc. which are valuable and transmitted from one generation to the next. But with a changing economy/society I would also guess that the genes/environments which matter also change.

Correct me if I'm wrong, but isn't it an error to make claims about the intergenerational transmission based on heritability quotients? After all, a trait may be highly heritable but not pass on from one generation to the next. This is because the relevant genes and environments may differ from one generation to the next. So I understand how we can make claims about genes and income within a generation, but by what logic can you extend this to intergenerational transmission?

What is Israeli Ashkenazi GDP?

Just looking at Ashkenazim doesn't control for demographic factors. What's the GDP when you're looking at Ashkenazim who aren't orthodox and aren't relatively new Russian immigrants? Compare that to the US Ashkenazim and the difference might not be caused by ethnic or religious factors. My general impression is that wealth differences within first world countries are due to cultural patterns rather than economic systems. The difference between democratic socialism and American-style mixed capitalism is dwarfed by the effects of cultural/demographics differences.

Thorfinn, Many Haredim are salaried employees. Would you mind linking to the Ashkenazi GDP data?

This is one of the cutting edge behavior genetics techniques. I believe an IVF study on smoking (maybe the same one) also found that later smoking/nicotine addiction is not effected by the prenatal environment. They should definitely do more of these. One thing I'm interested in is the possible problems/biases with these studies. Are there any relevant systematic differences between IVF mothers who use their own eggs vs donors? Also, might there be significant effects on development as result of using foreign eggs?

Also, there would almost surely be some significant differences in people who use IVF in any way which would make them a biased sample

The West Bank / Gaza stands out as a place where they having a a very high birth rate relative to their life expectancy

I wonder if there have been any studies comparing heritability estimates in industrialized societies to those in various pre-modern societies.

I also liked Steven Pinker's take on this. His view of the law is based more on motivation than blame. Even if a psychopath's genes are to blame, what matters is that society punishes this sort of behavior, thereby motivating it to occur less. This is especially important in the case of psychopaths, who can only be incentivized by punishment and reward and not by empathy.