Estimated kinship coefficients suggested that there were unknown relationships in the Guam and Kosrae data. Even though some pedigree information in the Kosrae data was known, more relationships were found by estimating kinship coefficients. Panel A and B of Figure 6 presents the estimated k-coefficients and Panel C and D of Figure 6 shows the cumulative distribution of the estimated kinship coefficients in the two samples. Estimation of k-coefficients allows us to quantify not only well-defined and possibly verifiable relatives such as parent-offspring, full sibling or cousin pairs, but also continuous degrees of relatedness. In the Guam data, the means and standard deviations of the estimated kinship coefficients are 0.023 (0.016) for the case group and 0.021 (0.020) for the control group with the case group having slightly higher average estimated kinship coefficients. This is consistent with the expectation that affected individuals may be more closely related because they share an ancestral mutation leading to the genetic disorder [Voight and Pritchard, 2005]. In the Kosrae data, the mean estimated kinship coefficients in the case group is 0.026 (0.025), which is also slightly higher than 0.024 (0.017) in the control group.
