The focal sample is labeled at the center of the image. Any genetically identical samples, or clones, of the focal sample can be viewed by clicking on the center of the image. The next circle shows immediate family members and the outer circle indicates relatives that are on the order of cousins or grandparents.
Family relationships are determined from a metric called identity by descent (IBD) (plink v1.9; Purcell et al. 2007). Specifically, the proportion IBD between two samples is the sum of probability of sharing both alleles at a locus (e.g., AA, AA) and 1/2 of the probability of sharing a single allele at a locus (e.g., AA, Aa). We use a second metric called genetic similarity, to identify putative family members as well as to identify clones. Genetic similarity is simply the number of shared alleles divided by the total number of alleles compared between two samples. Clones are designated as those samples that have extremely high genetic similarity. We set the threshold to be slightly higher than the average technical error rate of genotyping.