I am a fan of the “chute” theory, i.e., they come out of the chute with an innate intelligence level/personality which they can either develop or not based on the environment in which they find themselves. The exceptional child will further develop his/her natural intelligence in the most extreme conditions. However, the majority of kids who hit the genetic lottery jackpot are nurtured from day one which helps them immensely on their intellectual “journey”. For example, most kids are not going to sit and watch Nova at the age of four or five without an adult to guide them. A child who is fascinated by all things scientific and has a parent who either watches Nova or knows about Nova is way ahead of the game in comparison with a child of the same innate intelligence/curiosity who has parents who are watching reality television. Nurturing gives the diamond in the rough the éclat.
BTW - When my kids want to tease me, they throw an ain’t and a double negative into the conversation! My son always states that language is evolving, right after he lobs something that makes me cringe!
IMHO - When it comes to getting along in life, EQ is just as important as IQ.