blueprint: 3: the nature of nurture
blueprint by Robert Plomin- My notes while reading
Today I read a third of the third chapter. It started by stating that most published studies in top journals fail to replicate. He also discusses how some of Freud’s theories have not been replicated. His work has been replicated. His advice when reading a study or discussing one is to find out the statistical significance and the effect size. He talks abut how some researches make correlations between things that don’t exist or could be correlated to a third factor. Some people think environmental (nurture) causes certain things when a third factor could be genetic influence.
Genetics makes us rethink some of our basic assumptions on how the world around us shapes who we are. It is important to know correlation does not imply causation.
The classic example of a parent reading to a child correlates to how well they read in school. This can be looked at a few different ways. How much a parents reads to a child results in a child liking reading which then correlates to how well they read in school…or genetically…parents who like to read have children who like to read.
He went on to study seemingly environmental factors to see if genetic influence could be a cause instead. He studied life events to see if there are any genetic influences. He studied middle-age twins to see how they perceived major life events. 30% of identical twins vs 15% of fraternal twins perceived major life events the same way.
Divorce- 55% of identical twins vs 16% of fraternal twins. Certain personality traits account for a 1/3 of genetic influence on divorce. There isn’t a divorce gene. Heritability of divorce is 40%. A long way from 100 but it is still something..it isn’t all free will and environment.
He studied the amount of television viewing with adoptive children and their adoptive parents vs their biological parents. 30% of adoptive children and their biological parents were similar. 15% of adoptive children and their adoptive parents are similar. Even more astonishing is that birth mothers who haven’t seen their children since the first day are 15% similar to their adopted children. There isn’t a TV viewing gene. Turning the tv off or leaving it on pleases individually differently, in part to genetic influences.
