Gary Steinman is the
researcher who published the findings that diet may modify fraternal twinning rates. I just listened to him giving an interview on the radio, and he made the following points:
- Fraternal twinning rate seems to track basal levels of IGF
- Basal levels of IGF vary across populations, Sub-Saharan Africans have the highest rates, Asians the least, and twinning rates follow this trend
- When Yoruba move from the countryside to the city their twinning rates drop to the European level, while Japanese American twinning rates converge with white American twinning rates as opposed to Japanese twinning rates
