Intelligence, understood as measured IQ, can be predicted by the IQ of the parents, but there's more to think about.
I prefer to think about "smart" as something like the nexus of IQ, success and even self-reported happiness.
High IQ and trait conscientiousness are the best predictors of success (financial stability, if you like). From this, you can imagine that if conscientiousness can be encouraged, then it can display much the same success as high IQ.
I also hold that trait conscientiousness can be mimicked by membership in a coordinated structure. I suppose this would be like a business having cooperating employees. Their IQ and trait conscientiousness are limited as individuals, but collaboration makes them all more successful.
A single-parent (usually single-mother, because reasons) household is a predictor of less success, but also antisocial behaviour like criminality, and lower IQ. While #notall, it is most.
A second point can be made that mothers can have all the genetics in the world, but a single-parent household usually stunts childhood development.
That can be expanded to the idea that women are better caregivers to children, and men are better teachers to adolescents. Men can set boundaries and enforce consequences. Women create babies, and men create adults.
The snowflake-coddling that women/feminine (and an increasingly soft education and civilization) give will raise a certain kind of person that's different than the one demanded by men/masculine (with accountability, consequences, and competition).
We seat the responsibility of intelligence on genetics and learning (nature/nurture), without intuiting the in betweens:
- Two-role parenting (yes I'll go there). Feel free to think of this like two-personality, or two-specialized parenting.
- A child's socialization (which is largely done by other children, which is an odd issue to discuss)
.. I'd also add the nature of education as well as specific topics.
If you're ultimately talking about measurable IQ and the prediction of success of adults, they have to pass through a crucible of various things. These can be folded into "nurture" but should be thought of as independent topics which contribute to adult success and increased self-reported happiness.
Furthermore, a boy who doesn't engage in rough and tumble play will have a slightly underdeveloped brain (prefrontal cortex?), such that as he grows older he will exhibit hyperactivity-traits that responds well to Ritalin. That, on top of a school system that is engineered for girls (yes, seriously) and hostile to the healthy development of boys into men, well-adjusted men in particular are becoming rare. This can be seen as a general lowering of IQ in men, irrespective of parent IQ.
Women will raise their baby boys into distracted kids into measurably less successful men. And women wonder where all the good guys are..
Single parents (have to) spend less time with their children, leaving children to be raised by an incompetent schooling system (can the government be any good at anything?), resulting in poorer-quality adults that measure worse than they otherwise could.
- Two-point parenting
A childhood that includes physicality
- Like wrestling with dad
- Proper socialization (especially before four years of age)
- And a good breakfast
The encouragement of trait conscientiousness
- responsibility, consequences
- Environment ("safe")
- Intellectual engagement