The family poses two challenges to any theory of social justice. The egalitarian challenge focuses on the distribution of goods and opportunities between children born into different families. We can conceive those goods in a variety of ways. Economists tend to focus on expected income over the life-course; sociologists investigate chances of social mobility; philosophers typically think in more abstract terms such as resources or opportunities for well-being. But however we frame or measure the inequality, it is clear that children born into different families face unequal prospects....