Evolutionary psychologist Steven Pinker believes that, beyond genetics, parents don’t have much influence on their children’s personalities, intelligence, or life outcomes. Pinker is, of course committed to a scientific worldview, so he hasn’t sucked this belief out of his finger (as the Poles say) but provides actual evidence. For example, identical twin studies have shown again and again that identical twins raised together are no more similar than identical twins that are raised separately. And adopted siblings who are raised in the same family don’t end up similar at all. Children of immigrants, even those who never fully assimilate, end up speaking English with the language patterns and accents of their peers. So environment is important, but there is no strong evidence that parents are a very influential part of the environment. It would seem that abusive parents would have a huge effect on their children, but aside from making the children miserable, there is apparently little evidence that even parental abuse leaves any lasting mark on intelligence, personality, or life outcomes.
How about birth order? The idea that birth order is very important in determining all sorts of personality traits spread faster than the gluten-free diet fad. But a very large new study published in the Journal of Research in Personality analyzes the traits of 377,000 high school students and concludes that the effects of birth order on personality and intelligence are negligible. (http://www.sciencedirect.com/science/article/pii/S0092656615000525)
So it roughly boils down to this: The home environment, as it is influenced by parents, accounts for 0 to 10% of the variance in a child’s intelligence and personality. Genetics accounts for about 50%. The rest—40-50% comes from the surrounding culture and the child’s peer group.
All of this is extremely counter-intuitive and can elicit some very strong negative reactions, especially, of course, from parents of children who are doing very well. So expound on Pinker’s view of parental influence at dinner parties and other social events only if you don’t mind never being invited back.