Gynandromorphs in birds result from the fusion of two embryos with different sex chromosomes.

“Now, in a mammal, if that happened, the testice on the male side would masculinize everything by using hormones. The the clue that something else is going on in birds is that in this case, the you know, there's not been this blending. And when Art Arnold and others looked at the brains of uh Janandraorphs, sure enough, the sex differences where this region HBC for example uh is tends to be larger in males and females. In these animals, it was larger on one side of the body than”