Schlain states: "From an evolutionary point of view, homosexuality is a supreme paradox." If it had a genetic cause the trait would quickly go extinct. However, throughout history the rate of homosexuality has remained essentially constant, about 3% for males and 1% for females. It appears in all human societies. Thus even though there are those who are attempting to find a genetic cause, it is obvious that it doesn't exist. This historical data is too solid and profound. It will override any genetic investigations, which are based on loose correlations.