When sons and daughters have different fitness costs and benefits, selection may favor deviations from an even offspring sex ratio. Most theories on sex ratio manipulation focus on maternal strategies and sex-biased maternal allocation. Recent studies report paternal influences on both offspring sex ratio and post-partum sex-biased maternal allocation. We used long-term data on marked kangaroos to investigate if and how paternal mass and skeletal size, both determinants of male reproductive success, influenced (a) offspring...