Earlier quoted context omitted.
That wiki page lists a lot of evidence that a meaningful chunk is genetically causal. Is there a strong reason for me to think otherwise? Even the pessimistic numbers from gene mapping that are cited are .1-.2
I mean, start with the fact that it's a correlation statistic and not a causal statistic and just work your way back from that. Heritability --- of the kind with a research literature cite record --- is simply the ratio of phenotypical variation to genetic variation. The number of fingers on your hand is not, in that statistic, highly heritable. I don't think there's a Wikipedia cite that's going to get you over that…
And to the extent that research successfully isolates the genetic factors, we know it's not some outside factor causing a correlation, and we know it's not IQ causing genes. Anything isolated there is genes causing IQ.