A mothers' genetics determines how clever her children are, according to researchers, and the father makes no difference.
Women are more likely to transmit intelligence genes to their children because they are carried on the X chromosome and women have two of these, while men only have one.
But in addition to this, scientists now believe genes for advanced cognitive functions which are inherited from the father may be automatically deactivated.Concerned that people might not be like mice, researchers in Glasgow took a more human approach to exploring intelligence. They found the theories extrapolated from mice studies bear out in reality when they interviewed 12,686 young people between the ages of 14 and 22 every year from 1994. Despite taking into account several factors, from the participants education to their race and socio-economic status, the team still found the best predictor of intelligence was the IQ of the mother.
However, research also makes it clear that genetics are not the only determinant of intelligence - only 40 to 60 per cent of intelligence is estimated to be hereditary, leaving a similar chunk dependent on the environment.
But mothers have also been found to play an extremely significant role in this non-genetic part of intelligence, with some studies suggesting a secure bond between mother and child is intimately tied to intelligence.