An experimental study about the predictions from the multifactorial threshold model created by Falconer is presented, assuming that this model may explain the genetic mechanisms underlying the family aggregation of idiopathic epilepsies.We failed to confirm the following predictions from the falconer model: decreased prevalence of disease in relatives, proportional to decreased family links, and the order of birth effect. An heredity greater than 100% was calculated which is concordant with the presence of at least a locus with a major gen affect.Our results reject the multifactorial threshold effect and suggest the presence of a major gen or Mendelian effect. An analysis of complex segregation is suggested for future studies.