Genetic “Nature” is cultural too

I’ll ad­mit it: I am con­fused about ge­net­ics and her­i­ta­bil­ity. Not about the re­sults of the var­i­ous twin stud­ies—Scott sum­marises them as “~50% of the vari­a­tion is her­i­ta­ble and ~50% is due to non-shared en­vi­ron­ment”, which seems gen­er­ally cor­rect.

But I am con­fused about what this means in prac­tice, due to ar­gu­ments like “con­tacts are very im­por­tant for busi­ness suc­cess, rich peo­ple get much more con­tacts than poor peo­ple, yet busi­ness suc­cess is strongly cor­re­lated with ge­netic par­ent wealth” and such. As­sum­ing that ge­net­ics strongly de­ter­mines… most stuff… goes against so many things we know or think we know about how the world works. And by “we” I mean lots of differ­ent peo­ple with lots of differ­ent poli­ti­cal views—ge­netic de­ter­minism means, for in­stance, that cur­rent vari­a­tions in reg­u­la­tion and taxes are pretty unim­por­tant for in­di­vi­d­ual out­comes.

Now, there are many caveats about the ge­netic re­sults, par­tic­u­larly that they mea­sure the var­i­ance of a fac­tor rather than its ab­solute im­por­tance (and hence you get re­sults like vari­a­tion in nu­tri­tion be­ing al­most in­visi­ble as an ex­pla­na­tion for vari­a­tion in height), but it’s still hard to figure out what this all means.

Then we have Scott’s lat­est post, which points out that “non-shared en­vi­ron­ment” is not the same as “nur­ture”, since it in­cludes, for in­stance, dumb luck.

How­ever, “her­i­ta­ble” is not the same as as “na­ture”, ei­ther. For in­stance, sex­ism and racial prej­u­dices, if they are wide­spread, come un­der the “her­i­ta­ble” effects rather than the “en­vi­ron­ment” ones. And then it gets even more con­fus­ing.

Wide­spread prej­u­dice is not “en­vi­ron­ment”. Rarer prej­u­dice is.

For in­stance, imag­ine that we lived in a very sex­ist so­ciety where women were not al­lowed to work at all. Then there would be an ex­tremely high, al­most perfect, cor­re­la­tion be­tween “hav­ing a Y chro­mo­some” and “hav­ing a job”. But this would ob­vi­ously be sus­cep­ti­ble to a cul­tural fix.

Ob­vi­ously racial effects can have the same effect. It cov­ers any­thing visi­ble. So a high her­i­ta­bil­ity is com­pat­i­ble with ge­net­ics be­ing a cause of com­pe­tence, and/​or prej­u­dice against visi­ble ge­netic char­ac­ter­is­tics be­ing im­por­tant (“Our re­sults in­di­cate that we ei­ther live in a mer­i­toc­racy or a hive of prej­u­dice!”).

Note that as prej­u­dices get less wide­spread, they move from show­ing up on the ge­netic vari­a­tion, to show­ing up in the en­vi­ron­men­tal vari­a­tion side. So wide­spread prej­u­dices cre­ate a “na­ture” effect, rarer ones cre­ate a “nur­ture” effect. Evenly re­duc­ing the mag­ni­tude of a prej­u­dice, how­ever, doesn’t change the side it will show up on.

Po­si­tional ge­netic goods: Beauty… and IQ?

Let’s zoom in on one of those visi­ble ge­netic char­ac­ter­is­tics: beauty. As Robin Han­son is fond of point­ing out, beau­tiful peo­ple are more suc­cess­ful, and are judged as more com­pe­tent and co­op­er­a­tive than they ac­tu­ally are. There­fore if we have a gene that in­creases both beauty and IQ, we would ex­pect it’s im­pact on suc­cess to be high. In the pres­ence of such a gene, the cor­re­la­tion be­tween IQ and suc­cess would be higher than it should ob­jec­tively be. This sug­gest a (small) note of cau­tion on the “mu­ta­tion load” hy­pothe­ses; if re­duc­ing mu­ta­tion load in­creases fac­tors such as beauty, then we would ex­pect in­creased suc­cess with­out nec­es­sar­ily in­creased com­pe­tence.

But is it pos­si­ble that IQ it­self is in part a po­si­tional good? Con­sider that suc­cess doesn’t just de­pend on com­pe­tence, but on so­cial skills, abil­ity to pre­sent your­self well in an in­ter­view, and how man­agers and peers judge you. If IQ af­fects or co­varies with one or an­other of those skills, then we would be overem­pha­sis­ing the im­por­tance of IQ in com­pe­tence. Thus at­tempts to ge­net­i­cally boost IQ could give less im­pact than ex­pected. The per­son whose genome was changed would benefit, but at the (par­tial) ex­pense of ev­ery­one else.

Do peo­ple know of ex­per­i­ments (or planned ex­per­i­ments) that dis­en­tan­gle these is­sues?