Chimera Twins

Every once in a while a set of fraternal twin eggs merge into one embryo and the resulting person has two sets of DNA. It is possible for a Chimera to have different sets of DNA in different body parts, which can cause complication for body identification, DNA typing for organ transplants, crime investigation, etc. Researchers have no idea how common this is, but suppose that it is a reasonable percentage of all fraternal twin pregnancies, which would mean millions world-wide