While siblings can be close allies, they can also be significant competitors. They are also family members that are typically with us for most of our lives. Research has raised questions about the factors shaping sibling relationships, and an adaptationist perspective would predict a role for a number of factors including sex, genetic relatedness, and childhood co-residence. Recent work has highlighted sex differences with regard to conflict and emotional closeness, greater conflict among full-siblings than half-siblings, and a role for co-residence in increasing sibling altruism. This study examines levels of both sibling conflict and sibling cooperation as a function of respondent sex, sex of sibling, birth interval (or absolute age difference), co-residence, and relatedness. Results indicate that sibling conflict and cooperation may not be shaped by the same set of factors. Sibling conflict was predicted by own sex, sex of sibling, birth interval, duration of co-residence, and the degree of relatedness. Greater levels of conflict were reported by sisters, those closer in age, those who have co-resided longer, and full-siblings compared to half-siblings. However, sibling prosocialness was only predicted by sex and relatedness with females and full siblings reporting greater levels of sibling prosocialness. More research investigating patterns of conflict and cooperation within families using more ecologically valid cues are necessary to determine whether the two are operating under the same mechanism, sensitive to the same cues, or are, indeed, operating under different mechanisms.

虽然兄弟姐妹可以是亲密的盟友，但他们也可以是重要的竞争对手。他们也是我们一生中大部分时间通常与我们在一起的家庭成员。研究提出了关于影响兄弟姐妹关系的因素的问题，适应主义者的观点可以预测许多因素的作用，包括性别、遗传相关性和童年共同居住。最近的工作强调了在冲突和情感亲近方面的性别差异，全兄弟姐妹之间的冲突比半兄弟姐妹之间的冲突更大，以及同居在增加兄弟姐妹利他主义方面的作用。本研究考察了兄弟姐妹冲突和兄弟姐妹合作水平与受访者性别、兄弟姐妹性别、出生间隔（或绝对年龄差异）、共同居住地和亲缘关系的函数。结果表明，兄弟姐妹的冲突和合作可能不是由同一组因素形成的。兄弟姐妹冲突通过自己的性别、兄弟姐妹的性别、出生间隔、共同居住的持续时间和相关程度来预测。姐妹、年龄相近、同居时间更长的人以及同父异母的兄弟姐妹相比，所报告的冲突程度更高。然而，兄弟姐妹亲社会性只能通过性别和与报告更高水平的兄弟姐妹亲社会性的女性和全兄弟姐妹的关系来预测。更多调查冲突模式的研究 与半兄弟姐妹相比，全兄弟姐妹。然而，兄弟姐妹亲社会性只能通过性别和与报告更高水平的兄弟姐妹亲社会性的女性和全兄弟姐妹的关系来预测。更多调查冲突模式的研究 与半兄弟姐妹相比，全兄弟姐妹。然而，兄弟姐妹亲社会性只能通过性别和与报告更高水平的兄弟姐妹亲社会性的女性和全兄弟姐妹的关系来预测。更多调查冲突模式的研究与合作中的使用越来越多的家庭生态的有效线索是必要的，以确定两者是否是同一机制下运行，以相同的提示敏感，或者，实际上，不同机制下运行。