Genetic Variants Involved in Twinning (IMAGE) Cell Press 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. License Licensed content 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.