Anyone who discovers the game (at school, in a park, at his friend's place etc.) , has a lot of passion for it and demonstrates better-than-average aptitude will excel, regardless of the encouragement => Nature will beat nurture, hands-down.
However ... if you were asking if the environment kids are exposed to fosters an interest to play chess, that really depends on their school district / peer group.
For example, In Dallas, Texas (a fairly strong chess city) the "critical-mass" talent pool among kids seems to correlate well with areas such as Plano, Richardson where the scholastic/academic strength/competitiveness is relatively more cut-throat.
Having very active chess clubs that promote a lot of kid-based activities can't hurt either.
On the other hand, if your kid's peers are more into instant-gratification activities there's going to be less incentive for him to enjoy chess, let alone find somebody else who has a passion for the game to play it with.
I used to play chess alot when i was younger and wan a few school comps along the way. I never new of all the starting off moves as a child it was hard enough to get to grips with the rules and moves of peices!.
But as i grew up i joined a team but it never came to anything as then the players were more advanced than me and looked down on younger players. So i did quit and got on with other sports but i thought that if i was thought more on openings and defence i probably would of continued down the chess route.
But now i am older iv found my spark in chess again and do play alot now in my club and online and hope as my son grows il teach him chess and all that goes with it. Not just the rules and moves like i was taught when i was young do u think children get enough encouragement today to play chess or not