TALLAHASSEE, Fla. -- Reading bedtime stories, engaging in conversation and eating nightly dinners together are all positive ways in which parents interact with their children, but according to new research, none of these actions have any detectable influence on children's intelligence later in life.
Florida State University criminology professor Kevin Beaver examined a nationally representative sample of youth alongside a sample of adopted children from the National Longitudinal Study of Adolescent Health (Add Health) and found evidence to support the argument that IQ is not the result of parental socialization.
The study analyzed parenting behaviors and whether they had an effect on verbal intelligence as measured by the Picture Vocabulary Test (PVT). The IQ tests were administered to middle and high school students, and again when they were between the ages of 18 and 26.
"Previous research that has detected parenting-related behaviors affect intelligence is perhaps incorrect because it hasn't taken into account genetic transmission," Beaver said.
The findings were published in the article, "A closer look at the role of parenting-related influences on verbal intelligence over the life course: Results from an adoption-based research design," in the journal Intelligence.
The subject of how much influence parents have on intelligence has long been debated. Some research that shows parents who socialize their children in accordance with certain principles like reading with them often or having nightly family dinners, have children who are smarter than children whose parents do not do those things.
There is also an argument that it's not a parental socialization effect, but that intelligence is passed down from parent to children genetically, not socially. In order to test these two explanations, Beaver used an adoption-based research design.
"We thought this was a very interesting set up and when we tested these two competing hypotheses in this adoptive-based research design, we found there was no association between parenting and the child's intelligence later in life once we accounted for genetic influences," Beaver said.
Studying children who share no DNA with adoptive parents eliminates the possibility that parental socialization is really just a marker for genetic transmission.
"In previous research, it looks as though parenting is having an effect on child intelligence, but in reality the parents who are more intelligent are doing these things and it is masking the genetic transformation of intelligence to their children," Beaver said.
Does this mean parents can neglect or traumatize their children and it won't affect them?
"My response is no," Beaver said, "but the way you parent a child is not going to have a detectable effect on their IQ as long as that parenting is within normal bounds."
Beaver collaborated on the study with Joseph A. Schwartz from the University of Nebraska at Omaha's School of Criminology and Criminal Justice; Mohammed Said Al-Ghamdi and Ahmed Nezar Kobeisy from the Center for Social and Humanities Research and King Abdulaziz University in Saudi Arabia; Curtis S. Dunkel from Western Illinois University's Department of Psychology; and Dimitri van der Linden from Erasmus University's Institute of Psychology in The Netherlands.