The Mosuo, arguably the last surviving matrilineal society in China, offers interesting insights into kinship practices that support reproduction. In particular, the modes of courtship and reproduction of the traditional Mosuo revolve around a practice known as walking marriages, which involves no contract or obligations, where the men do not use social status or resources to court women, women do not expect commitment from men, and multiple sexual relationships are permitted for both sexes and seldom incite conflict. Children borne from walking marriages are cared for not so much by fathers but rather their mothers' brothers, and wealth and property are controlled by women and passed on to daughters rather than to sons. By analyzing how familial and mating practices interact with evolved preferences and ecological affordances, we highlight the ways that traditional Mosuo practices facilitate reproductive success despite differing vastly from those familiar to modern, industrialized societies. We suggest that cases that appear like evolutionary exceptions, such as the traditional Mosuo, can bring into question the mating practices and preferences we take for granted as relatively universal and prompt a nuanced understanding of how environments, culture, and evolution mutually constrain and shape one another.