About 1/4 of identical twins develop into mirror images of each other. As a result, they may have completely opposite physiological characteristics. For example, there may be a left-handed scorpion with a right-handed scorpion, and the hairpins on the head are opposite in direction, and there are corresponding birthmarks on both sides of the body.

In some rare and extreme cases, the organ and bone structure of mirrored twins may also be reversed.

However, scientists have noticed that the DNA of mirrored twins remains exactly the same.