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.
If you are seeking answers for personal information only, then the test can be done discreetly and privately between grandparent(s) and grandchild(ren) without any other person knowing. If you are needing a legal DNA test then the custodial parent or legal guardian will need to give written consent.