Duh, I dunno

There is sufficient evidence to indicate that one's intelligence is partly determined by heredity, partly by environment, and partly by the interaction between the two. 

Recent study proposed a list of 52 candidate genes linked to human intelligence:

Sniekers S. et al. Genome-wide association meta-analysis of 78,308 individuals identifies new loci and genes influencing human intelligence. Nature Genetics (2017)DOI:doi:10.1038/ng.3869

It has been known for over a century that that there is a strong genetic component to intelligence.  In fact, this is probably the most secure finding in the whole of psychology.   See Wikipedia for good summaries of this.

NB  The question needs better Topic tags.