We don't really know how common chimerism, because it is expensive to test for. It requires sampling many different tissues/ parts of the body and comparing th

We don't really know how common chimerism, because it is expensive to test for. It requires sampling many different tissues/ parts of the body and comparing the gentic material found in each. Some kinds of chimerism are easy to detect and are believed to be relatively common. See: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.149.9001&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.149...