Answer:
If you mean human chimeras, yes, contrary to the pretend-science folklore, there are many. The current best estimate is that at least 10-15% of individuals in the human population are chimeric. Human chimeras are people whose bodies are composed of cells of two different genotypes. They are dizygotic twin siblings who shared cells in the building of their embryo/s [may form one mixed-cell body, or two]. About one live birth in eight (best, conservative estimate) arises from a twin embryo. One in about 50 twin embryos results in a live twin birth. There are (again, conservative estimate) 10-12 single-born sole survivors of twin embryos for every live-born twin pair. It is likely that most of them are chimeric.
Human chimeras are extremely difficult to identify. The great majority of them have two normal, sibling cell lines of the same sex, and they are perfectly normal imperfect people. Every one identified to date has been found by accident… if one of the cell types is abnormal and generates a partial abnormality of development; if the cell lines are of different sex and located in visibly-sex-different parts of the body in sufficiently balanced numbers (normally, male cells greatly outgrow female cells in embryogenesis - experimental mixed-sex mouse chimeras almost always are born as normal-looking functional males). The first human chimera in the literature was discovered in 1953 due to different blood types in a 2:1 ratio (smaller-minority mixtures are hardly ever detected). Some famous cases have been found when whole families have been genotyped for legal or medical reasons and some parent-child pairs were found to be genetically inconsistent - usually child of one parent and genetically niece or nephew of the other. Direct samples with exquisitely sensitive testing have shown 8% in blood of live-born twins, 21% in triplet bloods, and 25-31% of monochorionic twins are dizygotic and thus necessarily chimeric. Because of the difficulties of identification, these are all minimal estimates, generally from blood only (chimerism when present need not be present in blood). Chimerism can be anywhere in the body, in any proportion from one per trillion to 50%.
http://www.intechopen.com/articles/show/title/human-embryogenesis