We analyze the intergenerational transmission of the strength of religion focusing on the interplay between family and peer effects. We develop a theoretical model suggesting that both peer quality and parental effort are of importance for the religious behavior of the children. We then bring the model to the data by using a very detailed dataset of adolescent friendship networks in the United States. We find that, for religious parents, the higher is the fraction of religious peers, the more parents put effort in transmitting their religiosity, indicating cultural complementarity. For non-religious parents, we obtain the reverse, indicating cultural substitutability. Concerning the success in transmitting the religious trait, we find that, for religious parents, the fraction of religious peers has only an indirect effect (through parental effort) while, for non-religious parents, there is a lower indirect effect and a statistically significant and sizeable direct effect of peers on the transmission of the non-religious trait.