According to research, a mother's genetics determines how clever her children are, while 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. In addition to this, scientists now believe genes for advanced cognitive functions which are inherited from the father may be automatically deactivated. 

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Photo source: By Peter van der Sluijs (Own work) [GFDL ( or CC BY-SA 3.0 (], via Wikimedia Commons