A while back I was watching one of my favorite channels "TLC", and I viewed a documentary called "I am my own twin".
It's about people who where shocked to find out that they were chimeric.
Basically a chimeric person is one who was supposed to be a fraternal twin. Of course fraternal twins are are the result of two eggs are fertilized with two sperm. But instead of both eggs developing separately, they fuse very early in development, and then develop as one person.
It was first that thought that chimeric's would have some sort of visual clue's like skin in different shades, or two different color eyes, but the medical community is finding out that this is not always the case.
There is also a condition called Mosaic where there is a slight variation cell to cell with DNA. As I understand it, with chimeric's there is a certain area where all the cells have a different set of DNA. For instance everywhere else in the body may have one set of DNA, but but if a sample is taken from hair, it may contain a completely different set of DNA than say the saliva.
I find this very interesting because how would one know that they are chimeric? And has anyone ever been found not guilty of a crime because the DNA sample retrieved did not come from the same organ as the sample left at a crime scene? And what about paternity tests? Surely some of those many men on the Maury Povitch show are chimeric...right?
I hope more research is done on chimeric's because there seems to be a lot more to be learned.