4 ms·
70% is actually on the low side of today’s results. Observed heritability is lower in early childhood (meaning the amount of variance in intelligence among chi
by xyzzyz 5y ago
70% is actually on the low side of today’s results. Observed heritability is lower in early childhood (meaning the amount of variance in intelligence among children explained by genes is “only” 20%-50%, “only” in quotes because it’s still large amount, as far as phenotypical traits are concerned), but grows to 80%+ in adulthood, even higher than that if you correct for attenuation (i.e. measurement error, which will always push the heritability down), and consider g factor instead of IQ scores (which is how intelligence is usually operationalized). IQ has been found to be exceedingly good vehicle to study the notion of intelligence, as the (most replicated finding in psychology) existence of positive manifold (google it) and g factor means that all non-contrived ways of measuring what humans usually understand intelligence is, yield pretty much the same thing, especially once you perform factor analysis.
Here is an overview paper by one of the leading researchers in the field (and one of the most distinguished researchers in psychology at large) Robert Plomin: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270739/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270739/
Unlike the rest of psychology, psychometry as a field does not have any kind of replication problem: all major results have been replicated many, many times on many different data sets. You can go to Google Scholar and find probably hundreds of replications (keyword is “heritability of intelligence”). Here is for example one from Japan: https://link.springer.com/article/10.1007/BF01067719 https://link.springer.com/article/10.1007/BF01067719 which finds heritability to be 50% among 12 year olds, here is one from Norway https://emilkirkegaard.dk/en/wp-content/uploads/On-the-question-of-secular-trends-in-the-heritability-of-intelligence-scores-A-study-of-Norwegian-twins.pdf https://emilkirkegaard.dk/en/wp-content/uploads/On-the-quest... finding 70% among military recruits, you can go on and on.
> I also think we can only accept that we're born different, but human. If we should aspire to anything, it should be to make life good for every individual, taking their capacities into account, not to give everyone an academic degree.
Clearly, but if the society denies reality, the result is expansion of higher education among people who can’t benefit from it, bullshit degrees, student debt, and general misery.
- qqqwerty 5y agoRobert Plomin is not without controversy: https://blogs.scientificamerican.com/beautiful-minds/there-is-no-nature-nurture-war/ https://blogs.scientificamerican.com/beautiful-minds/there-i...
- xyzzyz 5y agoWell, yes, because he studies intelligence and doesn’t mindlessly repeat socially acceptable nonsense. This necessarily means controversy. You’ll find that most researchers in that field are “controversial” in some way, but it really tells you more about how society views the results, not the people obtaining them.
- NoImmatureAdHom 5y agoI just want to say thank you to xyzzyz for the detail I was too tired to provide :-D
- pcrh 5y agoIt's interesting that you cite that Plomin article, since it actually concludes that only a small proportion of intelligence is genetically inherited. To quote: >Using years of education rather than intelligence per se, the meta-analysis mentioned earlier with 125 000 individuals in a discovery sample yielded a GPS that accounted for 2 and 3% in two independent samples.16 More variance in intelligence is likely to be explained with GPS derived from larger samples, whole-genome sequencing and more novel strategies such as using networks of functionally linked genes. Accounting for 2-3% of variance in intelligence through genetics is pretty weak support for genetics being an important contributor to variation in intelligence (however measured). The denialism here lies with those who wish to believe that intelligence is largely genetically determined, rather than socially and environmentally determined.
- xyzzyz 5y agoYou completely misunderstand the part you quote. What Plomin is saying is not that genetic heritability accounts for only 2-3% of the variance, but rather the GPSs, that is, the polygenic scores. What that means is that we can now point to concrete genes that contribute to intelligence, and assign them weights that tell us the significance of this contribution. This means that this 2-3% figure is not about reality of genetic contribution to intelligence on the ground, but rather about our explicit understanding thereof in 2014, when this article was originally published. Since then, our polygenic scores have significantly improved: for example, Lee et al in 2018 constructed polygenic scores that describe 11-13% of variance, a significant improvement over 2-3% result Plomin cites. There are probably even better results now, as the progress in the area is quick. Of course, 11-13% is still short of 80%+ that we already know is determined by genes, but our explicit understanding is slowly getting there. Importantly, as we get there, the goalposts of critics are constantly shifting: when we couldn’t point out to specific genes, the entire notion of heritability was attacked. Now that we can, the alleged problems are with spurious correlations resulting from population stratification etc. Alas, the science moves forward, despite fierce opposition. https://www.nature.com/articles/s41588-018-0147-3 https://www.nature.com/articles/s41588-018-0147-3 > The denialism here lies with those who wish to believe that intelligence is largely genetically determined, rather than socially and environmentally determined. I think your inability to distinguish between heritability and polygenic scores makes you thoroughly unqualified to make statements like that.