Chimerism in humans is only known to be present in 40-50 people around the entire WORLD.
Two different colored eyes is NOT a pure result of chimerism. It can also be due to heterochromia - the result of too much or too little pigment in the iris (or part of the iris) of one eye. This can be because of genetics or because of disease or injury.
Kiefer Sutherland also has 2 different colored eyes and he is not chimeric. We know he is not a chimeric because he has a living twin sister. It would be remarkably extraordinary odds in the trillions if there was a naturally occurring triplet that got merged with him or his sister or both while still in utero.
Eye color comes from the amount of pigment in the front part of the iris. Little or no pigment gives blue eyes, some pigment gives green and lots of pigment gives brown eyes. The pigment is made in melanocyte cells. If anything affects the health of the melanocytes in an eye, then that eye will look blue. Melanocytes are made while you are still a fetus and DNA determines just how many melanocytes you get. There are other factors where genetic code is turned on or off that affects this too, but sometimes something happens in utero that affects the melanocyte growth in one eye and that person is left with a blue eye when they should have both been brown or green.
When the melanocytes are affected by 2 sets of genes, it could then possibly result in 2 different colored eyes due to chimerism, but as stated, chimerism is VERY rare in humans.
