Yup … we just don’t know anything about human behavior … and don’t believe otherwise.
Some might argue for nature (“it is the genes … baby”) and some might argue for nurture (the environment). I don’t think we got any clue. None.
Identical twins who are reared in the same home only have a correlation of about 0.5 on personality tests. Now 0.5 is really high – but these are people with the exact same genes and the same upbringing. You’d think they would have even a higher correlation.
This information is care of Judith Rich Harris in her book “No Two Alike” (which I highly recommend). She goes on to state: “the identical twin of someone who has experienced a major depression has only a 40 percent chance of becoming seriously depressed. The identical twin of someone with schizophrenia has only a 48 percent chance of developing the disorder.”
So I stand here knowing that just don’t know jack about people…