New research may show that we get our intelligence from our mothers, and not from our fathers.
We already knew that because intelligence as a trait is carried by the X chromosome we were more likely to get it from our mothers (as women carry two X chromosomes, compared to men’s one), but now geneticists are saying intelligence is carried via what are known as conditioned genes.
Conditioned genes work conditionally. That is, sometimes they come from the mother, and sometimes they come from the father, but in the other instances, they are transmitted as deactivated genes.
Geneticists now say that the conditioned genes for advanced cognitive function may be naturally deactivated when passed on from our father, meaning the intelligence we get in our genes is coming solely from our mother.
As a result, intelligence is believed to be a conditioned gene we get from our mothers.
In one study of mice, for instance, researchers found genetically modified mice who were given extra maternal genes developed larger brains and heads, but had smaller bodies; mice who were given extra paternal genes, conversely, had smaller brains and heads, but larger bodies.