TWIN STUDIES ARE NOT ABOUT TWINS. Annalisa, knowing my interests, gave me this link to a post about a famous set of identical twins. They were born in 1933 and separated at six months, with one being raised by his mother in Germany and the other by his father in Trinidad. They met for a week when they were 20 and then chose not to see each other for 25 years. One reason that these twins are famous is that after living apart for almost fifty years, they turned out to have a number of idiosyncrasies in common. for example, they both dipped buttered toast in their coffee, they both had the same habit of storing rubber bands on their wrists, and they both liked to sneeze during uncomfortable silences.
This kind of study really doesn’t say anything about twins or the twin experience (I submit that twins are no more likely than other people to have odd habits like storing rubber bands on their wrists). What it says about individuals is fascinating. The coincidences seem to be too bizarre to be attributed to selecting a few hits from a myriad of behaviors. could there be a gene for putting rubber bands on wrists? And what would that say about evolution and natural selection?