This paper studies the role of family background in explaining differences in the willingness to compete. By combining data from a lab experiment with a representative sample of adolescents in Norway with official register data about family background, we show that family background is fundamental in two important ways. First, children from low socioeconomic status families are less willing to compete, even when controlling for confidence, performance, risk preferences, time preferences, social preferences, and psychological traits. Second, family background is crucial for understanding the observed large gender difference in willingness to compete. Girls from high socioeconomic status families are much less willing to compete than boys, whereas we do not find any gender difference in willingness to compete in low socioeconomic status families. Our data suggest that the main mechanism explaining the role of family background is that the father’s income and education has a large effect on the boys’ willingness to compete, but not on the girls. We do not find any effect of the mother’s socioeconomic characteristics on boys or girls.