Updated | Older fathers appear to have geekier sons, scientists have discovered. In a study of over 30,000 twins, researchers found boys who had older fathers scored higher on the "geek index"—and that the older the father, the higher the score. (The geek effect was only seen in boys.)
By the age of 12, boys with older fathers were found to be more intelligent, more focused on their interests and were less concerned about whether or not they fitted in with their peers.
While there has been much research showing the negative impact having children later in life can have—including increased risk of autism and schizophrenia—little has been done into the potential benefits.
The latest study, published in the journal Translational Psychiatry on Tuesday, indicates there are evolutionary advantages for men having children later in life.
Scientists from the U.K and the U.S. collected cognitive and behavioral data on 15,000 sets of twins. At the age of 12, they completed tests measuring their "geeky" traits, including their non-verbal IQ, their focus on subjects of interest and their social aloofness. Parents were asked how they were perceived by their peers and if they had interests that dominated their time.
From this, the researchers were able to produce a "geek index score" for each child in the study and to compare it to the age of the parents.
Their findings showed a correlation between the age of the father and the geekiness of the sons, with a positive correlation between the two—the older the father, the geekier the son. They also noticed geek traits appeared more after the age of 45.
Geeky boys did better in school exams, especially STEM (Science, Technology, Engineering and Maths) subjects, suggesting they would be more successful in their careers as adults.
The authors say there are several limitations to the study. They were not able to determine whether the geek effect extended beyond secondary education and future success, adding it "remains possible that personality traits associated with GI [geek index] cease to be advantageous in later life." For example, being flexible and socially aware rather than focusing on a single goal may provide more benefits in the work environment in the long-term.
They also said they could not verify whether geek traits were associated with things like poor emotional and social functioning.
However, they said the findings show there may be some benefits associated with having an older father.
Study author Magdalena Janecka tells Newsweek: "Our primary hypothesis is that higher levels of those 'geeky' traits in offspring of older men are mainly due is due to characteristics of the fathers themselves. Men who decide to delay fatherhood often do so due to their extended career and educational pursuits, and likely themselves display higher levels of 'geekiness.'"
Another implication of the study is the link between autism and higher paternal age. The scientists were not able to measure the link directly, but say that some of the genes relating to geekiness and autism overlap, and that these genes may be more prevalent in older fathers.
If a child is only born with some of these genes, it may help them succeed in school, but if they get a "higher dose," they may be more at risk of autism.
This link could also explain why the geek effect was only seen in boys. "We think the reasons for this may be similar to those why females seem protected from autism in general," Janecka says. "For some reason, there could be a selective passage of those traits from fathers to son, but biologically, we still do not know how this could work."
She also says girls with older fathers may well be geeky too, just in different ways: "Another possibility is that we have not measured 'geekiness' in a way that allows to capture its manifestation in females—there remains a caveat that daughters of older men are just as geeky, but we could not capture it in the current study."
The study, Janecka adds, does not mean men should put off having children until they are older in the hope of having more intelligent sons. "Those findings should definitely not be taken to guide individual decisions about parenthood," she says. "Effects we are describing are visible in large samples, but may operate very differently in cases of individual families."
Patrik Magnusson, from the Karolinska Institutet in Sweden, has studied the link between parental age and autism risk. Commenting on the study, he tells Newsweek: "That geekiness is associated with school success is not strange at all, to be a geek is defined as being someone with skills that are very well suited for school. That geekiness is associated with having an old father is a little stranger."
He says this link is likely down to several different factors, including geekiness being heritable. Another could be that men who get the chance to become fathers at a later age need to show "special positive skills."
"This special skill may be genetic and transmitted to the offspring," he says. "Also, fathers that wait with kids may predominantly be fathers that have spent time studying or spent time developing ideas or business in favour of a the more common family life. Such personality is likely genetically inherited."
This story has been updated to include comments from Patrik Magnusson.
