The intelligence gene is carried on the X chromosome. Women have two of these while men have one, it is more likely that mothers are the key here.
Fathers may not be very impressed with the research that suggests that a mother's genetics determines a child's intelligence. The study is based on the concept that the intelligence gene is carried on the X chromosome and because women have two of these while men have just one, it is more likely that mothers are the key players here. Moreover, scientists believe that genes for advanced cognitive functions, that are inherited from a father, maybe automatically deactivated, reports Independent. To understand this better, we need to know what conditioned genes are. It's a category of genes that are believed to work only if they come from a mother in a few instances and fathers in other cases. And intelligence is one such conditioned gene that comes from a mother, while the paternal gene remains dormant in the child, per reports.
To test this hypothesis, a study was conducted by scientists on genetically-modified mice. The embryonic test subjects which were administered predominantly maternal genetic material ended up developing a disproportionately larger brain and cranium while having a much smaller body. Meanwhile, subjects that were given disproportionate amounts of paternal genetic material developed a larger body while having a smaller cranium and brain.
That being said, the size of the brain and the cranium were not the only determining factors for the researcher's conclusion. They first identified six areas of the brain that would contain only maternal or paternal genes. Interestingly, they did not find any paternal genetic material within the brain's cerebral cortex, which is responsible for executive functions like language, logical reasoning, planning, and advanced thinking. Researchers in Glasglow did consider the fact that the people may not accept the test as they were conducted on mice. So, they took a more human-approach while exploring the intelligence factor and found that the theories from the mice study bore similarities in reality.
Researched interviewed a group of 12,686 people aged 14 to 22 every year from 1994. During every follow-up meeting, they would observe the subjects' intellectual development while considering many factors like their ethnicity, socio-economic status, and education. Ultimately, they found that the mother’s IQ was the best predictor of their intelligence. But research also made it clear that genetics is not the only determinant of intelligence. Apparently, only 40 to 60 percent of one intelligence has been estimated to be hereditary, thus leaving a portion of the determining factor on the environment.
Even in this non-genetic portion of intelligence, mothers were found to have played an extremely significant role. A few studies suggested that a secure bond between a mother and a child was intimately related to intelligence. Although the findings continue to be scrutinized, according to Power of Positivity, research carried out at the University of Washington found that the security that comes from an emotional bond between a mother and her baby is crucial for the growth of a few parts of the brain. The researchers analyzed a group of moms and their relationship with children for seven years. It was found that children, who received emotional support and had their intellectual needs fulfilled, had a hippocampus which was 10 percent bigger than kids whose mothers were distant emotionally. The hippocampus is a region of the brain which is associated with stress response, memory, and learning.
Having a strong bond with mothers imparts a sense of security in children, allowing them to reach their full potential. Of course, a father also plays a huge role in nurturing kids, and researchers noted that several other genes-determined traits, from emotions to intuitions, can be inherited from fathers. These traits are also an important factor in unlocking the potential intelligence of a child. So no need to despair, fathers!