 In order to distinguish biological differences from social/psychological ones and to talk about the latter, feminists appropriated the term ‘gender’. Psychologists writing on transsexuality were the first to employ gender terminology in this sense. Until the 1960s, ‘gender’ was often used to refer to masculine and feminine words, like le and la in French. However, in order to explain why some people felt that they were ‘trapped in the wrong bodies’, the psychologist Robert Stoller (1968) began using the terms ‘sex’ to pick out biological traits and ‘gender’ to pick out the amount of femininity and masculinity a person exhibited. Although (by and large) a person’s sex and gender complemented each other, separating out these terms seemed to make theoretical sense allowing Stoller to explain the phenomenon of transsexuality: transsexuals’ sex and gender simply don’t match.