Not "only", but yes, there are studies attributing variation in intelligence in significant part to genetics.
https://ghr.nlm.nih.gov/primer/traits/intelligence
> These studies suggest that genetic factors underlie about 50 percent of the difference in intelligence among individuals.
Not "only", but yes, there are studies attributing variation in intelligence in significant part to genetics.
https://ghr.nlm.nih.gov/primer/traits/intelligence
> These studies suggest that genetic factors underlie about 50 percent of the difference in intelligence among individuals.