Competition among developing seeds and sibling rivalry within multiovulated ovaries can be deleterious for both the maternal parent and thesiblings. Increased genetic relatedness of seeds within the ovary may fosterkin selection and reduce the deleterious consequences of sibling competition.The pollen parent may also be selected for siring all progeny within a fruit.I propose a series of hypotheses to explain the evolution of a number of reproductive traits in angiosperms in the context of kin selection and sibling rivalrywithin the ovaries of angiosperms. I present evidence to show that a singlepollen parent, indeed, often sires seeds within multiovulated ovaries. Varioustypes of pollen aggregations and transfer of such pollen masses to the stigmasof flowers by specialized pollinators make this increased genetic relatednesspossible. An alternative mode to reduce sibling rivalry may be the reductionof ovule number to one, an evolutionary trend that has independentlyoccurred many times in flowering plants. Finally, I build on previously established correlations to predict two sets of correlations among reproductivetraits. In the first case, large showy flowers, transfer of pollen en masse byspecialized pollinators, and multiovulated ovaries and multisided fruitsseem to be correlated. In the second case, the previously established correlations among small and inconspicuous flowers, pollination by wind, wateror generalist insects, flowers and fruits with few or single ovules and seeds,respectively, may also include monoecy or dioecy. Although correlationsamong many of these traits have been established in the past, I invoke kinselection and sibling competition to explain the evolution of correlated traitsas two distinct evolutionary pathways in angiosperms.