A child’s intellect does descend from their parents, but is it true that it primarily descends from the mother? What about the father?
In China, many pondered to find the answer after an article appeared on microblogging site Sina Weibo, which stated that genetics from the mother had three times more influence in determining the child’s intellectuality than from the father. The article said, “To determine the intellectuality of a child, we can refer to the mother. For men who consider themselves unintellectual, it is recommended for them to find a smarter wife.”
However, is it really true? Let’s take a look at the explanation.
The link between the X chromosome and intelligence
Explanation given by the article mentioned above is that the intellectuality traits are carried on by the X chromosome(female chromosome genetic carrier). However, it does not quote any scientific references or sources for every statement it makes. In the article, Satoshi Kanazawa said general intellectuality was known to be inherited and the genes that affected common intellectuality were suspected to be carried by the X chromosome.
This means that boys inherit their intelligence only from the mother, while girls inherit their general intelligence from both mom and dad. Therefore, women should be more of an influence on intelligence compared to men.
Si Dayong, a lecturer on Evolution at Jilin University, refutes the claims made in the Weibo article, “Descendants from a certain gender have nothing to do with X and Y chromosomes, but some sort of epigenetic traits [traits that are not caused by changes in DNA sequence, but more on changes in the genes expression],” he said. “I haven’t yet found a certain trait that can be dominant from either the mother of father.”
Research on derived intellectuality
A study published in an academic journal of Behavior Science in 1982 sees a correlation between parent and child. It has come to attention that IQ correlation between mother and child is a little higher at 0.464 compared to father and child at 0.423.
“I don’t think this small difference is considered statistically significant,” said Si. “Other than that, genetic inheritance is something random and complicated, out of a man’s imagination.”
Although it has been long believed that heredity contribute to a child’s intellectual, yet newer study found that it actually lacks contribution than predicted before.
A study in 2013 done by researchers from University of Queensland conducted a DNA analysis and IQ test results from more than 18,000 children from Australia, Netherlands, UK and US. As a result, they found that heredity contributed around 20-40 percent from children’s various IQ, lower than expected before.
Researchers later conclude that there is no single gen variant that can strongly predict child’s intellectuality, and that intellectuality that is inherited genetically is a cumulative effect from different variation of genes.
Zhao Bowen, a researcher at Shenzhen Huada Gene Research Institute, elaborates a finding in a 2014 article at knowgene.com. “To this very day, no DNA sites directly determines the origin of human intelligence,” he said. “Parent’s Genetic influence on children’s intelligence could be more or less, and a child’s intellectuality tends to have a normal distribution curve, with parents inherited intellectuality as a median.”
Xu Gelin, a doctor of neurology at Nanjing General Hospital of Nanjing Military Command, emphasized in Jinling Evening News Report published in November 2014, that genetic heredity random and complex, and that both parents had various level of influence on the child’s genetics. “For instance, if the mother has higher IQ, and the father has lower IQ, chances are their children will fall in between,” said Xu.
This statement caused a contradiction with what said by Weibo, stating that to determine the intellectuality of a child, we can refer to the mother. “Of course, it is well approved that a child with both high IQ parents will be pretty smart in general.”
Other factors affecting a child’s intellectuality
Dr. Rachel Brouwer from the Psychiatric Department of Utrecht University Medical Center in the Netherlands states that it’s true that you can predict a child’s IQ, but it’s based more on the parent’s IQ rather than changes in their brain on a group level. “So in general, brilliant parents will produce brilliant children as well.
However, this is not absolute, it could be that low intellectual parents turn out to have children with high IQ and vice versa.” Dr. Brouwer also emphasized that the environment contribute an impact to intellectuality, even though it will lessen as the child grows.
Senior lecturer at Melbourne University’s Graduate School of Education Catherine Scott puts a stronger emphasis to the environment and history. “Children don’t only share genes with the parents,” she said. “They also share family and environment. This also links closely with their food and their mother’s food.”
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