A recent genetics study has revealed that our intelligence is derived from the female X chromosome. A mother’s genetics determines how clever her children are and fathers make no difference, according to the study. Women are more likely to transmit intelligence genes because they are carried out on the X chromosome and since women have two, they are more likely to pass on their intelligence.
The X chromosome has over a thousand genes and until recently, the doctors believed that both the parents are responsible for and contribute equally to their child’s intelligence.
Scientists now believe that genes which are responsible for advanced cognitive functions that are inherited from the father are possibly automatically de-activated. The activated genes have an impact on genetic development and the de-activated genes don’t.
If there is a single characteristic which is affected via the mother, the father genes will automatically get de-activated. If a single characteristic is affected via the father, the maternal genes are later de-activated.
There is a category of genes known as the ‘conditioned genes’ and are thought to work only if they come from the mother in some cases and the father in other cases. Intelligence is believed to be in the genes which come from the mother.
The University of Cambridge studied brain development and genomic conditioning in 1984. Cambridge scientists concluded that maternal genetics give more material to brain centers.
Laboratory studies on genetically modified mice showed that those with an extra dose of maternal genes ended up having bigger brains and heads but little bodies and vice versa; those with an extra dose of paternal genes had smaller heads and brains but bigger bodies.
Researchers found that there were cells which contained only maternal or paternal genes in six different parts of the mouse brains which controlled different cognitive functions.
Cells which were associated with the paternal genes involved functions such as sex, food, and aggression and were found in the limbic system. However, researchers did not find any paternal cells in the cerebral cortex where the majority of advanced cognitive functions such as thinking, reasoning, thought, language and planning take place.
One could argue that humans and mice are very different and to prove that the same theory applies to people, researchers in Glasgow took a more human approach to exploring intelligence. They found that the theories that they derived from the mice experiment actually apply in reality when they interviewed over 12,686 young people between the ages of 14 and 22 every year from 1994.
The team still concluded that the best predictor of intelligence was the IQ of the mother.
Research also makes it clear that genetics are not the only determinant of intelligence.
Researchers from the University of Washington found that a secure and emotional bond between a mother and child was extremely crucial for growth in some parts of the brain. They analyzed two groups over a period of seven years and found that children who were supported emotionally and had their intellectual/ developmental requirements filled had a 10% larger hippocampus as compared to those whose mothers were emotionally distant.
It is about 40-60% which is hereditary and the rest is up to the environment and nurture but it is safe to conclude that we owe our mothers a lot cause they are the reason we are intelligent.