So far, only one species with this rarity has been found, which has allowed scientists to think that sexual orientation could begin to organize in the embryo of each individual before even sex hormones intervene.
The clue has been provided by a specimen of the Mandarin diamond bird or Taeniopygia guttata castanotis , which is male on its right side , where it has a shiny testicle and feathers, and female on its left side , with an ovary and less showy feathers. It has been proven that their cerebral hemispheres are different, since the left one has more developed neural circuits that control singing.
