In this paper, we contribute to the literature on how institutions impact development by providing micro-level evidence of how informal institutions can affect development outcomes. More specifically, we measure how the informal institution of privileging food consumption by men (and boys) affects child development, as measured by weight/height data. In many parts of the world, informal institutions discriminate against women, inhibiting their individual development and acquisition of human capital. Here, we study the effect of an informal institution of privileging the food consumption of men over women in rural Africa. We hypothesize that the effect of this informal institution trickles down to children, thus privileging the physical development of boys compared to girls. In addition, we argue that as female children get older, they become more malnourished. Our analysis draws from two datasets: an original collection of data on 513 children between the ages of six weeks to ten years from Bubaare, Uganda; and survey and anthropometric data of children from 819 households in Mchinji, Malawi. Using linear regression models, we find robust support for both of our hypotheses. Girls of the same age and height do worse on physical outcomes compared to boys, and the disparity is greater in older children. These findings have important policy implications for agencies fighting malnutrition and promoting development, including policy suggestions for international agencies, foreign donors, and non-governmental actors in combating malnutrition in developing countries.