Ok so the genotype is the same (same DNA) but the phenotype is different (what you see). It's more complex than this but there are all sorts of ways that genes express themselves and how this can be changed. A good dose of phenol or benzene can do wonders to your genetic material. A trip to Windscale (sorry Selafield) to inspect the inside of the reactor vessel etc all has an effect. DNA testing would probably never look at the entire sequence anyway. It would look at enough to give near unique markers. Using a "drill down" technique to gradually exclude until only one remains. ie normal number of gene pairs (not many people live with duff code in here but there are some) male vs female (50%) blood group etc Why use actual matching until you need to, it's expensive. You get down to a handful and test those on a wider range of codes. You hope the samples are good and the genes haven't been damaged or contaminated. Don't rely on the science. The science is our tool NOT us of the science. We already rely too much on the technology, science, methods etc. This is not a scientific way of working. Anyway have fun!! Hwyl