It's the 21st century, and we are still being told that there are no differences between men and women, and that any differences we think exist are simply the result of social constructs--to claim otherwise is considered sexist and misogynistic. Sociologists point to disparities in the workforce, claiming these inequalities are the result of a patriarchal society. Yet what if these disparities could be explained through men and women's own choices and inclinations? What if, instead of simply resulting from the patriarchy, sexism, or societal-imposed gender roles, these differences can be explained through a multitude of factors--a mix of complex and interconnected variables? A look at the current scientific literature on sex differences and their origins, this paper reviews data from the fields of biology, psychology, evolutionary behavioral science, neuroendocrinology, and neurology, showing the complicated and nuanced nature of average sex differences between males and females.