Chickens can also be gynandromorphous, and only about 1 in 10,000 chickens are born with this rare genetic abnormality. The interesting thing is that the researchers expected to find a mutation of some kind, but instead came across chickens that are half-male and half-female with completely different anatomy on two halves of the body. The difference was in their body shape, plumage and muscle structure. According to the doctors, this might not only lead us to some interesting discoveries about human health in the future, but can also provide insight into how birds develop.
Source: BBC News