This article from Smithsonian Magazine summarizes how twin studies have been used untangle the influences of genes and the environment on particular traits. Twins have been used in the study of eugenics, I.Q., eating disorders, obesity, sexual orientation, and the effect of spaceflight on the body.
Resource: WHO Gender and Genetics
The World Health Organization website has a concise but comprehensive overview of the relationship between genetics, sex, and gender. This website presents an overview of the major ethical, legal, and social implications associated with gender and genetics. This website is a useful resource for students researching sex and gender in the context of genetics or health.