White matter month*: Transgendered individuals have white matter microstructure resembling halfway between male and female.

Thomas Beattie and family expecting third child
Thomas Beattie and family expecting third child.   Image via Momlogic http://photos. momlogic.com/ galleries/thomas_   beatie #166661

And yet another reason to strike down Prop 8 – unconstitutionally vague: gender identity versus biological gender is a very blurry line.

People who seek to become transgendered have white matter resembling the other gender — males have female-like white matter, and females have male-like white matter, prior to beginning the process.

Rametti G, Carrillo B, Gómez-Gil E, Junque C, Zubiarre-Elorza L, Segovia S, Gomez A, Guillamon A. (2010).The microstructure of white matter in male to female transsexuals before cross-sex hormonal treatment. A DTI study. Journal of Psychiatric Research in press

Our results show that the white matter microstructure pattern in untreated MtF transsexuals falls halfway between the pattern of male and female controls. The nature of these differences suggests that some fasciculi do not complete the masculinization process in MtF transsexuals during brain development.

Rametti G, Carrillo B, Gómez-Gil E, Junque C, Segovia S, Gomez A, Guillamon A. 2011. White matter microstructure in female to male transsexuals before cross-sex hormonal treatment. A diffusion tensor imaging study. Journal of Psychiatric Research 45: 199-204.

Our results show that the white matter microstructure pattern in untreated FtM transsexuals is closer to the pattern of subjects who share their gender identity (males) than those who share their biological sex (females). Our results provide evidence for an inherent difference in the brain structure of FtM transsexuals.

*January is “White Matter Month” somewhat arbitrarily named in honor of white flower days or whatever when stores give discounts on sheets and towels.