Sonless families may pose another gendered demographic dividend. As fertility declines, families with only daughters are likely to grow. In turn, patriarchal family systems may weaken when many families are unable to engage in patriarchal practices. I examine some of these theorized dynamics in India. Sonless families did grow as fertility declined, reaching 10 percent in India as a whole in 2015 and approaching 20 percent in states with earlier fertility declines. I also identify a substantial influence of children's sex on mothers' expectations of old-age support. Using panel data from the India Human Development Survey (IHDS), I compare women's expectations after they had children to earlier expectations when they did not yet have children. Women with sons kept or further embraced patriarchal expectations that a son would provide support. Sonless mothers largely gave up patriarchal expectations, turning to daughters or away from children altogether.