Pesquisas que apontam para evidências biológicas da transexualidade.

Alguns trechos dos artigos nos links abaixo são especialmente esclarecedores.
Evidentemente, há mais estudos apontando para esta direção e só uma pesquisa mais aprofundada poderá cobrir a maior parte deles. Aqui são dadas apenas algumas sugestões.

"...This paper represents the first comprehensive review of the scientific evidence that gender identity is a biological phenomenon," explains corresponding author Joshua D. Safer, MD, FACP. "As such it provides one of the most convincing arguments to date for all medical providers to gain the transgender medicine skills necessary to provide good care for these individuals," he added. ..." Boston University Medical Center. "Transgender: Evidence on the biological nature of gender identity." ScienceDaily. ScienceDaily, 13 February 2015.

http://www.sciencedaily.com/rele.../2015/02/150213112317.htm

"What’s in a Gender? Studies of Brain Structure Find Evidence for Neurological Basis of Transgender Identity"

https://www.academia.edu/7346016/What_s_in_a_Gender_Studies_of_Brain_Structure_Find_Evidence_for_Neurological_Basis_of_Transgender_Identity

"Transsexual differences caught on brain scan"

https://www.newscientist.com/article/dn20032-transsexual-differences-caught-on-brain-scan/

'Results of transsexual brain studies"

"EDIT: As of October 2013 this article is slated for a re-writing. Please do keep in mind that this article was written in 2011. Its information and language usage may be old. Subscribe to our RSS feed, or follow us on G+, Facebook, Twitter or Tumblr to be updated when this article is revised."

http://openmindedhealth.com/2012/01/results-of-transsexual-brain-studies/

"A Sex Difference in the Human Brain and its Relation to Transsexuality"

J.-N. Zhou, M.A. Hofman, L.J. Gooren and D.F. Swaab

http://www.transgendercare.com/medical/hormonal/brain_sex_diff.htm

"Male-to-Female Transsexuals Have Female Neuron Numbers in a Limbic Nucleus"

Frank P. M. Kruijver, Jiang-Ning Zhou, Chris W. Pool, Michel A. Hofman, Louis J. G. Gooren, and Dick F. Swaab

http://press.endocrine.org/doi/full/10.1210/jcem.85.5.6564

"Imaging the Transgender Brain"

"...Except, that is, for one area, the putamen, a deep brain structure that forms part of the basal ganglia – known for its wide range of functions and connections to the frontal lobes and action control areas.

Because we know so little about the neuroscience of self-image and gender-identity it’s almost impossible to draw any conclusions for the fact that this specific area seems more ‘feminine’, or that the majority of the other areas seem more ‘masculine’ in terms of size.

What this study does do, however, is add to the increasing evidence that there are some detectable neurological differences in the brains of transgendered people. We’re just not in a position to say much about the significance of this yet. ..."

In 

http://mindhacks.com/2009/04/05/imaging-the-transgendered-brain/

http://skeptoid.com/episodes/4463

http://med.stanford.edu/news/all-news/2006/07/transgender-experience-led-stanford-scientist-to-critique-gender-difference.html