Sex is a word that refers to the biological differences between male and female: the visible difference in genitalia, the related difference in procreative function. 'Gender' however is a matter of culture: it refers to social classification into 'masculine' and 'feminine' (Oakley, 1972: 16).

             The main reason that we need to distinguish between 'sex and gender' is because many differences between and males and females are not biological in origin. But the need to distinguish between 'sex' and 'gender' has become more apparent in today's society, because of the increased number of people who choose to live their lives as members of the opposite sex. This has caused people to rethink some of their theories on 'sex' and 'gender'. It uses to be thought "That people are male or female can usually be judged by referring to biological evidence. That they are masculine or feminine cannot be judged in the same way: the criteria are cultural differing with time and place. The constancy of sex must be admitted, but so must also the variability of gender" (Oakley, 1972: 16). But now of course you can change those biological characteristics that distinguish what sex you are. So sex is no longer the constant state that it use to be, so now 'sex' and 'gender' are both variables and that has to be taken into account when looking at distinguishing between the two. It is argued that you are born a certain sex, but you learn a certain gender. Although sex strongly influences gender, if you are a male you will probably act in a masculine way, and if you are a female you will probably act in a feminine way. One of the big arguments is because you are born male does that make you behave in a masculine way? Or is it the way you are treated being a male that makes you behave in a masculine way? And same goes for females and femininity. There are people who believe we can't separate 'sex' from 'gender' and that they are one in the same.