Environment definitely plays a big role. It’s a balance of environment and individual capabilities. When assessing intellectual contributions, I think people tend to underestimate environmental and structural factors (were you working at a place like bell labs, did you go to an elite school, etc.) and overestimate the “innate” abilities or gifts of the individual.

If you look at intellectual history, almost every genius worked in an environment in which they were surrounded by equally brilliant minds, or had ample correspondence with other thinkers of their time (of course there are exceptions).