Similarly, in the case of diallelic markers, ϕest was closer to ϕped when more markers were used. Figure 2 shows the the relation between ϕest and ϕped in the diallelic case of CEPH families with 500, 5,000 and 16,977 SNP markers (Panel B). Panel B also shows the similar results of kinship estimation from 5,000 and 16,977 markers, which indicates that the number of SNPs does not need to be too large. The estimate of the kinship coefficient for parent-offspring was more accurate than that for full-siblings in the CEPH data. In the case of the 5,000 diallelic marker panel, the means of the estimated kinship coefficients were 0.243 (0.026, N=8) for full-sibling and 0.243 (0.008, N=87) for parent-offspring. The means of the parent-offspring and full-sibling relationships were similar, but that for the parent-offspring relationship had a smaller standard deviation even with the larger sample size. However, kinship coefficients were overestimated for unrelated pairs for both the simulated and CEPH data.
