Most Reported Genetic Associations with Intelligence are Probably False

Re:Most Reported Genetic Associations with Intelligence are ... by tehwalrus on Tuesday October 08, 2013 @11:09AM (#6515474)

I would assume that many behaviours (including language itself) are inherited - and yet have nothing whatever to do with genetics. How would you control for this?

Only last week, we had an article on here about how vocabulary in very young children was a function of how much parents talked to their children - with marked differences between economic groups[1]. There are many many systematic errors in this kind of data, and I have no good (ethical) suggestions in how to eliminate them.

[1] https://news.ycombinator.com/item?id=6480155

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Re:Most Reported Genetic Associations with Intelligence are ... by tokenadult on Tuesday October 08, 2013 @11:35AM (#6515657)

How would you control for this?

The classic way to control for cultural and in-family influences in studies of human behavior genetics is to look for the rare cases of monozygotic ("identical") twins brought up in separate households after adoption. Those studies of monozygotic twins reared apart (MZA twins) set a MAXIMUM figure for the heritability of any trait of interest--because the genes are as similar as they can be between two different human individuals, but the environments, even in separate households, may not be as maximally different as they could be in influence on the trait in question. There is a whole book about the most famous study of identical twins reared apart, which took place at my alma mater while I was an undergraduate and postgraduate student there (in other subjects).

http://www.hup.harvard.edu/catalog.php?isbn=9780674055469

As some people will remember from the press reports at the time, the most culturally variant upbringing two of the separated twins, Oskar and Jack, studied by the Minnesota researchers received was one twin being raised as a Jew, and the other twin being brought up in Nazi Germany and becoming a member of the Hitler Youth.

http://online.wsj.com/article/SB1000142405270230355210457743...

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Re:Most Reported Genetic Associations with Intelligence are ... by tehwalrus on Tuesday October 08, 2013 @11:51AM (#6515773)

I guess I was saying that the rarity of this happening in the real world makes good statistics difficult (which are essential in biological systems,) and of course intervening to force better statistics is a rather horrific proposition.

Thank you for the links though, I'll have a read!

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Re:Most Reported Genetic Associations with Intelligence are ... by rch on Tuesday October 08, 2013 @11:35AM (#6515656)

Check out 'The Blank Slate' by Steven Pinker. It presents a fairly thorough accounting of how these sort of conclusions may be reached.

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Re:Most Reported Genetic Associations with Intelligence are ... by tehwalrus on Tuesday October 08, 2013 @11:52AM (#6515781)

I have that on a shelf somewhere, but I don't think I persevered to the end. I'll have another look, thanks!

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Re:Most Reported Genetic Associations with Intelligence are ... by scott_s on Tuesday October 08, 2013 @12:02PM (#6515843)

I think you're using "inherited" to mean "comes from your parents in any way," but that's not what it means in this context. If something is learned from your parents, then it would not be consider an "inherited trait".

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Re:Most Reported Genetic Associations with Intelligence are ... by tehwalrus on Wednesday October 09, 2013 @11:06AM (#6521661)

going by the "receiving money when people die" thing, I'd say its anything your relatives give to you. I'm sure in a biological science context people mean only genetic/biochemical things (biochemical - e.g. heroin addiction), but my point is that it's difficult to separate out the truly biological ones from the learned ones in most cases.

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Re:Most Reported Genetic Associations with Intelligence are ... by scott_s on Thursday October 10, 2013 @06:27PM (#6530423)

That's a fine point to make - separating out variables is hard. But when talking in a biological context, you're going to confuse people if you use the colloquial definition of "inherited".

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