A 2010 study, Garcia-Falgueras and Swaab asserted that "the fetal brain develops during the intrauterine period in the male direction through a direct action of testosterone on the developing nerve cells, or in the female direction through the absence of this hormone surge.
Dalam abstraksi studinya tahun 2010, Garcia-Falgueras dan Swaab menyatakan, "otak janin berkembang selama masa intrauterin ke arah laki-laki melalui kerja testosteron pada sel-sel saraf yang berkembang, atau ke arah perempuan melalui ketiadaan hormon ini.