A couple of teasers... We first describe the major sources of sex differences in the brain including: gonadal hormones, sex chromosomes, and environment. We explain classical "organizational" & "activational" roles of hormones, but note influence of exogenous endocrine compounds (HC, HRT, GAHT).

We explain the role of sex chromosomes in gonadal development, and their hormone-independent effects incl: i) sex-biased gene expression (Y-linked genes, X-escapees) & ii) effects on cellular environment (eg. repressor complexes involved in X-inactivation). We discuss chr complements beyond XX/XY.