Some sociologists argue that non-intact family structures during childhood have a negative effect on adult children's civic engagement, since they undermine, and in some cases prevent, the processes and activities through which parents shape their children's political attitudes and orientations. In this paper, we evaluate this hypothesis on the basis of longitudinal data from the German Socio-Economic Panel. In a first step, we construct various measures of family structure during childhood, and perform both cross-sectional and sibling difference analyses for different indicators of young adults' civic engagement. Both exercises reveal a significant negative relationship between growing up in a non-intact family and children's political engagement as adults. In a second step, we implement a novel technique – proposed by Oster (2014) – for evaluating robustness of results to omitted variable bias. The distinctive feature of this technique is that it accounts for both coefficient movements and movements in R-squared values after the inclusion of controls. Results suggest that our estimates do not suffer from omitted variable bias.