Identical twin Jack Yufe recently died. He was born in the 1930s in Trinidad. His Jewish father and German mother divorced when he was six months. His brother, Oskar Stohr, was taken back to Germany and raised by his mother’s Nazi family.
The twins met years later, and despite many difficulties in trying to reach out to each other, they [and the nurture/nature academics] noticed several unusual similarities. This has been documented with many twins separated at birth and is used as evidence that nature–our DNA–has a strong effect on our personalities and behaviors.
I’d like to suggest another possibility that I haven’t seen studied but is recognized by all the mothers I’ve spoken to on the topic. It’s that those nine months in utero, when the two fetuses are experiencing their early development at the same time in the same place, hearing the same voices, experiencing the same tastes, feeling the same joy, tension, and fears as their mother, has a profound effect on the future development of the child.
The twin studies have found greater similarities among identical than fraternal twins in some traits. I wonder if this might at least be partly explained by the greater number of shared placentas among the identical twins.