The human CNV study in Nature is highlighted in the science media this week. Researchers seem surprised at the amount of variation observed. “It would seem the assumption that the DNA of any two humans is 99.9% similar in content and identity no longer holds”, observes the article. I’m not sure that we ever held that assumption.
Should we be so surprised? I think it’s worth remembering that any genome sequence is really a consensus based on a small sub-population. Perhaps this idea that individuals are almost genetically identical stems from there. I seem to recall from high school biology that genomes get shuffled during meiosis. In a sense, doesn’t every cell also have its own genome, reflecting its own environmental history?