From ScienceDaily: http://www.sciencedaily.com/releases/2013/11/131107204241.htm
In brief, it turns out that a single person can have more than one genotype, or individual genetic code. Somatic mutations, which occur when our cells are exposed to agents like sunlight, "hard" radiation, viruses, certain chemicals, etc., can lead to those changed / damaged cells multiplying and spreading. Cancer is one of the best-known cases, but there are relatively benign forms of such mutations as well.
The really startling thing this study found is that the same kinds
of mutations occur in completely unrelated individuals. From the article:
Because somatic changes are thought to happen at random, scientists do not expect unrelated people to exhibit the same mutations. Williams and colleagues analyzed the same 10 tissue samples in two unrelated people. They found several identical mutations, and detected these repeated mutations only in kidney, liver and skeletal body tissues. Their research examined "mitochondrial DNA" (mtDNA) -- a part of DNA that is only inherited from the mother. Technically all women would share mtDNA from one common female ancestor, but mutations have resulted in differences. The importance of Williams' finding is that these tissue-specific, recurrent, common mutations in mtDNA among unrelated study subjects -- only detected in three body tissues -- are "not likely being developed and maintained through purely random processes," according to Williams. They indicate "a completely different model …. a decidedly non-random process that results in particular mutations, but only in specific tissues."
So many questions to be asked, so many answers to be sought. I really
don't want us to screw up our current civilization, because we're learning amazing things literally every day, and greater discoveries yet are likely just over the horizon.