This paper brings together the notion of ‘son preference’ and the complementary concept of ‘daughter aversion’ to provide an explanation for larger Muslim, relative to Hindu, families in India. Just as sons bring ‘benefits’ to their parents, daughters impose ‘costs’ and complementing a desire to have sons is a desire not to have daughters. Consequently, the desire for sons increases family size while the fear of daughters limits it. A formal model, in which these two countervailing forces act so as to determine equilibrium family size and composition, is developed. Qualitative evidence about Hindus and Muslims in their attitudes towards sons and daughters is presented; as are quantitative results from a Poisson regression model estimated on data for 10,548 women who had attained their equilibrium family size. The analysis concludes that higher Muslim fertility compared to Hindus may in reality reflect significantly lower levels of daughter aversion among this community.