Dizygotic twinning, marital stage and status and coital rates.

An attempt is made to isolate and quantify a positive correlation of parental coital rate with dizygotic twinning probability, by considering the variations of DZ twinning with marital stage and status. It is concluded that if the coital rate of young women is doubled, their DZ twinning probability is increased by a factor of very roughly 25-30%.