A chimeric individual is one that has two sets of genetic makeup in their body. These individuals develop during the fertilization stage of growth and development. This occurs when two ova are each, separately, fertilized by a sperm. The two zygotes fuse, implant and begin to develop as one blastocyst. As the blastocyst develops and differentiate, some parts of the blastocyte are developed from the genetic material of one of the cell lines while other parts develop from the other cell line. Therefore, the fetus will have particular tissues and organs with different genotype from others.
