The problem is that they only seem to be looking for a link to genetic differences, and are ignoring the fact that the sex of your brain (and the sex you develop as physically) is not directly determined by genes, but instead depends on androgen levels during the time your prenatal development was taking place. While genetic factors can affect fetal androgen production, so can environmental factors such as exposure to external hormones, and in today's world, laden with chemicals and hormone-based medicines, environmental factors are probably more significant than genes. If they don't understand that, it suggests that they're very ill informed, and are probably working outside their area of expertise. I doubt whether they'll find anything, beyond possibly a link to things we already know about, such as mutations in the androgen receptor gene, mutations that affect testicular development, and mutations that give rise to congenital adrenal hyperplasia. It would be far more informative if they were to look at things like illnesses and trauma while the mother was pregnant, and whether she was given any hormones or hormone modulating drugs.
