New research published in Psychology Spot has found that genes behave differently depending on whether they're passed from your mum or dad - and when it comes to smarts, that can only come from mum.
That's because the genes that determine intelligence are found on the X chromosomes, and women have two of those while men only have one. Even if smarts are passed on from the father's side, it simply stays "deactivated" because of the gender of the origin.
Another study from Scotland in 1994 surveyed subjects aged 14 to 22 and found that the best indicator of their IQ's was the IQ's of their mothers.
But it's not just genetics that factor into a child's intelligence. Previous studies have also found that mothers' physical and emotional contact with their children can impact how well they learn.
The University of Minnesota found that children who've formed strong bonds with their mothers have the ability to play complex symbolic games by the age of two.