No two cells are ever genetically identical. Within a common hyper-mutable region, tandem repeats, the mutation rate is 10^-3 to 10^-5. There are over 10^5 tandem repeats in the genome, and therefore at least one mutation is expected for every cell division. Many other types of hyper-mutable regions exist in the human genome.

In this research they only examine one form of genetic variation, SNPs. These findings only reflect a small proportion of the somatic variation present in the body.

There is no real surprise in these results, but the data may nevertheless be useful!