The Biology of Gender Identity
Between the (Gender) Lines: the Science of Transgender Identity – An article by a third-year graduate student at Harvard that overviews the research showing biological causes of transgender identity. The article is concise and highly readable, and provides links to the research referenced.
Gene Variants Provide Insight into Brain, Body Incongruence in Transgender People. Feb. 2020 article in Science Daily discusses new research showing that the incongruence transgender individuals experience, because their brain indicates they are one sex and their body another, may be related to estrogen receptor pathways in the brain.
Is gender identity biologically hard-wired? A 9-minute video from PBS News (2015) looking at the research.