For whatever it's worth, since you cited Plomin, if you Google him (or that study) you'll get a lot of interesting writing about how not-especially-useful that result turns out to be. A good shot/chaser on polygenetic behavior indicators is Shalizi's "g" writing, which is mostly about the distinction between exploratory and confirmatory data analysis, which seems pertinent.
IQ is 50 to 80% inherited [1]. (We can only predict about 10% of it with genetics [2].)
[1] https://en.wikipedia.org/wiki/Heritability_of_IQ
[2] https://www.nature.com/articles/nrg.2017.104