gsa writes "Why do men prefer blonds? Why are most suicide bombers Muslim? Psychology Today analyzes some of these non-politically-correct questions in this essay about ten politically-incorrect truths about human nature. It turns out there may be an evolutionary or psychological explanation for all of these observations. For example, 'Sociologists and demographers have discovered that couples who have at least one son face significantly less risk of divorce than couples who have only daughters. Why is this? ... There is relatively little that a father (or mother) can do to keep a daughter youthful or make her more physically attractive. The continued presence of (and investment by) the father is therefore important for the son, but not as crucial for the daughter. The presence of sons thus deters divorce and departure of the father from the family more than the presence of daughters, and this effect tends to be stronger among wealthy families.'" Update: 07/08 05:51 GMT by Z :Removed sentence that misquoted article.