Sex is annotated as different from gender in the Oxford English Dictionary where it says sex "tends now to refer to biological differences, while . . . often refers to cultural or social ones."
A working definition in use by the World Health Organization (WHO) for its work is that "'ex' refers to the biological and physiological characteristics that define men and women" and that "'ale' and 'female' are sex categories".
Scientific research shows an individual's sex influences his or her behaviour.
Read more about this topic: Sex And Gender Distinction