Proportion of offspring sired by the unrelated male (B) in male triplets in which two brothers were matched with an unrelated male (AAB, n =54). The B-male sired on average half of the offspring produced by the female, leaving the two brothers to share the other half. This distribution of paternity deviated significantly from an equalitarian distribution of paternity across the three males (i.e. 033, dashed line, z = 3.99, P < 0.001), and was independent of male stock (i.e. sep, spa). Vertical bars = se.