Lifetime Earnings Are 40-50% Heritable
link.springer.com
link.springer.com
https://www.researchgate.net/profile/Bruce_Sacerdote/publica...
Incidentally IQ is also strongly correlated with lifetime earnings. In fact if you can know only one thing about a job candidate, it's the measure you should pick.
You want someone who will do the work well and will help the company succeed.
Indeed, you could argue that a high earner is, all else being equal, something you should avoid selecting as a hiring manager.
I have worked with people who had higher salaries than I did who were clearly much worse at the job (a backend architect at a past gig told me that UTF-8 supported only 256 characters, and refused to acknowledge it when I pointed out sources that showed he was wrong).
But it actually is addressed by other studies such as adoption studies that show generally the same results. And, of course, there are potential problems with adoption studies too. But wouldn't it be suspicious if every[1] method of studying the problem we tried gives fairly close numbers but only because they all happen to be biased by the same amount in the same direction?
[1]GWASes give lower numbers but we know that there are many sorts of genetic interaction they don't cover so this is expected.
(1) Statistically compare the population of twins vs the population of non-twins. The paper I linked to has more specifics on this, but twins earn similar amounts of money, live similar lengths of time, do similarly well in exams vs. non-twins, so it any twin-specific genetic effect has to simultaneously be strong enough to cause this discrepancy, but not strong enough to impact population means.
(2) Compare adoptees to genetic offspring of parents. This has the same issue that you pointed out (maybe there is something specific about adoptees) but the two together find roughly similar effect magnitudes, which reenforce each-other. I'm actually a bit more concerned about adoption being less 'clean' an identification strategy than twin studies, because it's a complicated social process.
(3) Look at genetic variation at population level and find genetic markers that explain variation, using Mendelian randomization as identification strategy - this is technically very challenging, and has only recently become feasible. So far research have only been able to explain around 7% of IQ for example with specific genetic markers, but it will be interesting to see if this creeps up as the field matures.
The big puzzle here is the large variation that we between cultures - moving time-periods, or countries can significantly change your life-expectancy, earnings, test-scores or even IQ. I don't know how to reconcile this with the strange finding of this research strand is that family level environmental effects (shared environment) seem to be much less important than the conventional wisdom would suggest.
Links https://www.sciencedirect.com/science/article/pii/B008042707... (gated)
https://en.wikipedia.org/wiki/Mendelian_randomization
https://www.newscientist.com/article/2163484-found-more-than...
I'm no expert, but that seems like the biggest issue. I mean the study says that income is heritable, which by its very nature would affect the environment that right?
Can you explain this a bit more?
> The classical twin design compares the similarity of monozygotic (identical) and dizygotic (fraternal) twins. If identical twins are considerably more similar than fraternal twins (which is found for most traits), this implicates that genes play an important role in these traits. By comparing many hundreds of families with twins, researchers can then understand more about the roles of genetic effects, shared environment, and unique environment in shaping behavior.
> (i.e., within-pair genetic differences are not correlated with the within-pair environmental differences; see e.g. Stenberg (2013) who stresses the importance of this assumption for the interpretation of heritability estimates), and iv)
So this is only about whether sibling differences are correlated with the environment -- which seems much more reasonable. On the other hand, the very next one is problematic:
> [We assume] there is no assortative mating. The last assumption would not hold if the genotypes of the parents were correlated (Posthuma et al. 2003).
Tendency of parents to have some genetic sorting seems both easy to measure and quite likely - why not dig in to its impact?
Finally, another thing that makes the result hard to generalize (emphasis added):
> We show that in the relatively equitable economic and institutional environment of Finland, the share of variance of lifetime earnings explained by education is clearly less than a tenth (in our data).
The authors acknowledge that they were measuring the size of effect in an environment that has far less variation in the variable than many. This seems like a good place to confirm the existence of an effect, but a bad place to be confident of its size, and a worse place from which to generalize about more heterogenous environments. Compare Finland's GINI index (income concentration) to US, UK, or China to get an idea of how much more variation there is in those societies: https://www.indexmundi.com/facts/indicators/SI.POV.GINI/comp...
What does this mean?
edit: but it seems they do not use adoption data.
That way you have 3 variables, genes (identical twins have same genes, fraternal twins just have similar), the home and parenting part, and all other parts that aren't related to your parents at all. This study in particular found that just the genes and the other factors were relevant, while the home wasn't.
Environment has not been entirely separated out here it seems. And while a comparison of fraternal and identical twins detangles things somewhat it doesn't completely.
My intuition is that a person's personality and aptitudes (around 50% heritable according to many studies) can help them to take advantage of their environment in certain ways. So it's not that environment doesn't matter at all. It's just that people with varying attributes will leverage their environment in different ways, leading to different outcomes.
It would be even more interesting to me to see the personality profiles of the children compared against their future earnings. My guess is there would be a strong correlation since personality -> interests -> career choices.
Then it would just so happen that identical twins have similar personalities. Leading to the results we see here.
Admittedly I'm hopeful that if we could figure out the correlation between personality and environment maybe we could shift our focus away from the unhealthy extremes of 100% nurture (leads to children being pushed by their parents to fit into a mold that may not suit them) and 100% nature (genetic fatalism leads to apathy and hopelessness). Instead what if we took a child's natural gifts and personality profile into account and tailored their environment to maximize their potential within those constraints? Seems like a more hopeful and useful path.
Boas was wrong.
> Genetic Influence on Human Psychological Traits
> There is now a large body of evidence that supports the conclusion that individual differences in most, if not all, reliably measured psychological traits, normal and abnormal, are substantively influenced by genetic factors. This fact has important implications for research and theory building in psychology, as evidence of genetic influence unleashes a cascade of questions regarding the sources of variance in such traits. A brief list of those questions is provided, and representative findings regarding genetic and environmental influences are presented for the domains of personality, intelligence, psychological interests, psychiatric illnesses, and social attitudes. These findings are consistent with those reported for the traits of other species and for many human physical traits, suggesting that they may represent a general biological phenomenon.
http://humancond.org/_media/papers/bouchard04_genetic_influe...
Compare, say, humans and ants.
Ants seem to have a ROM of sorts: software embedded in genes and immutable within a single organism's lifetime. They only inhabit the world of atoms.
Humans have a ROM to cover basic functions but also writable memory. We can change our behaviors within a single lifetime and then if that wasn't cool enough we can also TRANSMIT those behaviors without genes via the world of thought and ideas (language).
We ought to never forget that. Fatalism binds us too strongly to the physical world. It's a bad path that leads to nihilism (struggle against nature is futile), cruelty (everyone deserves their lot in life since if they were capable of more they would have achieved it), and despair (self-actualization is impossible, I am an automaton).
Of course it might not apply to a few special cases like if you inherited a billion dollars, but for 99% of us that is not the case.
How on earth could you possibly know this?
> Actually just said by Donald Trump Jr: "I wish my name was Hunter Biden. I could go abroad and make millions off my father's presidency. I'd be a really rich guy"
You can probably make some reasonable intelligence estimates off that sort of statement.
Makes complete sense to me.
Not sure what's racist about that though. It's just reality, facts about humans.
This is really not how IQ testing is done. Rather than guessing about correlations in the environment to IQ and working backwards to come up with an estimate for IQ, generally IQ tests are administered.
Raven's Progressive Matrices [1] is an example of a test that doesn't depend upon knowledge of tea service items.
[1] https://en.wikipedia.org/wiki/Raven%27s_Progressive_Matrices
If you're born into a very poor home, and to use your example, a poor black home in the US, I'm not convinced my IQ would overcome my environmental handicap.
How many times out of 10 would you expect to make it to college and earn a high paying job while growing up black in some of the rougher city's and neighborhoods of the US?