So rather than try to improve the science we should just ignore the question?
Experiments require resources which are limited. And after the falsification of intelligence genes, it makes sense to find a psychological cause for delay of gratification first, and test other logical explanations second.
Edit: I was wrong. Reading Wikipedia article (https://en.wikipedia.org/wiki/Heritability_of_IQ), it seems intelligence is related to both genes and enviroment.