Figure 4

Fraction of correct Sib2 inferences: the fraction of Sib2 SNPs that can be correctly identified when Sib1 is (a)homozygous major or (b)heterozygous. Each line represents use of distinct data–inclusion or exclusion of Sib1 genotypes, and use of population-specific or global allele frequency data. Without Sib1 genotypes, homozygous major inferences would always be incorrect at MAF ≥ 0.33 and heterozygous inferences would always incorrect at MAF ≤ 0.33. At many allele frequencies, use of Sib1 genotypes dramatically improves Sib2 inferences.