Over and over again, we have been told that our personality traits, our idiosyncrasies, our weaknesses, and our merits are all because of our genome. Supposedly, if someone studies our DNA, they will know exactly the type of person we are, but is that really true? According to new research, it’s not. Researchers have discovered that is extremely common for a person to have mosaicism, or multiple genomes. In other words, chimeras make up a higher fraction of people than scientists originally thought. Some have many variations, or mutations, in certain parts of the body, and some people even have genomes that are from other people. People can acquire a different set of genes along with their original genes as early as in the womb. Previously, there were just hints about the idea of multiple genomes, but the hints have turned into definite statements. The evidence of multiple genomes is changing the way scientists think. Links between rare diseases and multiple genomes are becoming apparent. After figuring this out, scientists are figuring out links between more common disorders and genome multiplicity. Although many forms of cancer and other diseases are linked to mosaicism, most instances of multiple genomes are benign. It is also changing the way that forensic scientists view DNA evidence in crime investigations. The biggest change of all is perhaps that scientists now have to consider that DNA from a finger prick may not be the same DNA in a muscle cell or brain cell. This means that scientists can’t tell what is happening in all the organs just from a simple blood test or test from one organ. They can’t be certain of what is happening in other parts of the body. However, scientists are hard at work discovering more powerful ways to investigate our multiple genomes.