Gender is an essential determinant of social outcomes, including health. Besides, gender can be separated neither from biology nor from other social identifiers as ethnicity, culture, age or social economic class (United Nations,1995). The concepts of ‘sex’ and ‘gender’ are a face of the nature–culture debate, with the presumption that sex is unchangeable, whereas gender is constructed and can change. Recently, evolutionary psychologists have proposed biological explanations of behaviour by arguing that social constructions may have a biological origin (Taylor et al, 2000). The phenotype is the result of complex interactions between genotype and environment, leading to a lifelong remodelling of our epigenomes, and numerous dimorphic genes expression might be under the control of sex-specific epigenetic marks (Gabory et al, 2009)
