Genetic Variants Involved in Twinning (image) Cell Press Share Print E-Mail Caption This graphic depicts the conclusions of the Mbarek et al. study on the genetic basis of fraternal twinning. Credit Hamdi Mbarek Usage Restrictions Credit Required. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.