Figure 3

Sib-ship identifiability surfaces: these surfaces describe the probability of sib-ship as a function of M, the number of partially matched independent SNPs (between two individuals) and MAF. We show this across three sample size pools–N = (a)100,000; (b)10,000,000; (c)6,000,000,000 people. At high MAFs even very large increases in the potential sample pool size will not prevent sib-ship confirmation with relatively few matched SNPs. For example, if loci with MAF = 0.25 are selected, the number of matched SNPs to confirm sib-ship with p = 0.999 is 50 with a candidate pool of 100,000 and increases to only 80, in a group of 6 billion.