An example of a polygenic trait is human skin color variation. Several genes factor into determining a person's natural skin color, so modifying only one of those genes can change skin color slightly or in some cases, such as for SLC24A5, moderately.
Case 1 â The Alleged Father has Recently Passed Away. If less than a week has passed since the deceased died, then if permission can be obtained, fingernail cuttings and a hair sample with root attached can be used to extract DNA samples to establish paternity. It is a more complex procedure than a buccal swab, but the DNA matching is just as accurate.
But a critical test subject is either deceased or otherwise unavailable to submit a DNA sample. This is where the principles of genetic testing can sometimes help you get DNA indirectly. Read on to learn more about the various options for getting a valid DNA sample. Human DNA Sources. Today, most DNA testing laboratories collect DNA from willing subjects through cheek cells, saliva, or sometimes blood.