I've never been overly impressed with the BSTc analysis - not only are the numbers too small, but aside from a paper or two in the 1990s, there has been no corroborating study that lends weight to it, and by the authors own admission, there are plenty of explanations for the observed evidence.
The in-utero hormone flush hypothesis has always felt similarly weak - it's an explanation, but it's almost impossible to verify. It would require numerous strokes of luck to identify a candidate or two, and then decades to follow them from pregnancy through to early adulthood. (a process which by itself may have a significant influence on the subjects)
So, when this story popped up, I was initially feeling pretty skeptical about whatever it was going to say (in fact I was worried that it was going to be more on the BSTc study).
After studying the DNA of the male-to-female transsexuals, genetic experts from Prince Henry's Institute at the Monash Medical Centre found they were more likely to have a longer version of a gene known to modify the action of sex hormone testosterone.
The genetic abnormality on the androgen receptor gene is believed to lower testosterone action during fetal development, and "under-masculinise" the person's brain, leading them to feel like a female trapped in a male body.
Actually, this makes a lot more sense as an explanation of causality than the other options that have been put forth to date. It fits well into the "Occam's Razor" principle - it's simple, covers a wide range of possibilities. Even better, it's relatively easy to pursue further. (The BSTc investigations could only be done post-mortem, and long term follow-up research with transsexuals is notoriously difficult)
Further, this particular finding also meshes well with the all too common narrative that so many transsexuals put forth that they "knew something was wrong" from very early ages - often before any awareness of social gender distinctions would be expected.
The work is far from conclusive at this time, and we should always be cautious with early results like this. I am reassured by the breadth of sample size used. (No, it's not a large sample in general population terms, but for a study involving such a tiny fraction of the population, it's actually a pretty good size for a starting point)
This writer is now going to have to go and find the actual article and study it - I'm sure that whatever is in the news is only the surface of the story.