Bill Rice addressed various genetic conflicts between the sexes, and he illustrated his ideas by interesting data on intersexual developmental conflicts in Drosophila. When the two sexes are selected toward different optima of a phenotypic trait, and when the genes underlying the trait are expressed in both sexes, then alleles will typically be favourable to one sex, while harmful to the other. Rice showed experimental data demonstrating that such sexually antagonistic alleles do indeed occur in Drosophila, and are in fact quite abundant. This finding may have important implications for theoretical models, such as the good-genes model of sexual selection.