A genetic chimera is an organism that contains cells with different genetic compositions. This can occur naturally, such as when two embryos fuse together in the womb, resulting in one individual with mixed DNA from both embryos. Chimeras can also be created artificially in laboratories for research purposes. In medicine, genetic chimeras are studied for their potential to understand diseases and develop treatments. For example, scientists may create chimeric animals, like mice, that carry human genes to study human diseases. This research helps in advancing fields like genetic therapy and transplantation.