Does every cell in our body contain the identical genome we inherited from our parents at conception? Maybe not:DNA Double Take
Chimeras—organisms with more than one genome—are now known to be more common than science used to believe. They can arise when the DNA of twins mingles in the womb. They don’t even have to be identical twins. The DNA of a fetus can migrate into the mother’s cells. Recipients of marrow donation have been found to have genetic traces of the donors in other parts of their bodies.
Mosaicism, in which mutations cause some cells to have different genomes from the rest of the body, can give rise to some diseases such as forms of cancer. However, it can also be harmless or beneficial.
Among other real-world implications, the NEW YORK TIMES article discusses how the presence of more than one genome in a single person could complicate the use of DNA profiling in criminal investigations.
Extrapolate to alien species, in which these phenomena might be normal and universal instead of anomalous, and we can imagine meeting “individuals” that are really two or more people in a single body.
Margaret L. CarterCarter's Crypt