Australian researchers have identified a gene involved in testosterone action that might be responsible for male-to-female transsexualism. The longer versions of this gene are associated with reduced action of testosterone which has an effect on gender development in the womb. Comparison of the long version of the androgen receptor gene from the M2F transsexual participants with 258 controls showed its significant link with transsexualism. The study has also proven that certain brain structures in M2F transsexual people are more “female like”.