Pairwise comparison of genotypes of within-pair (WP) males, extra-pair (EP) sires, and neighboring males that were excluded as EP sires at nests of House Wrens. For comparisons between EP sires and WP males, n = 20. For comparisons involving excluded neighbors, n = 17. Shown are mean values (± SE) for each class of males as a group and the mean difference between individuals in different classes in pairwise comparisons at focal nests. Values for males of different classes were compared by paired t-tests. All P values are one-tailed.