According to the causal theory of parenthood, people incur parental obligations by causing children to exist. Proponents of the causal theory often argue that gamete donors have special obligations to their genetic offspring. In response, many defenders of current gamete donation practices would reject the causal theory. In particular, they may invoke the 'too many parents problem': many people who causally contribute to the existence of children - for instance, fertility doctors - do not thereby incur parental obligations. This article argues that the conclusions commonly drawn by causal theorists, and by their critics, are premature. Causal theorists have a promising response to the too many parents problem. This response, however, defuses the moral concern that many causal theorists have raised about gamete donation. A similar point, it is argued, applies to Rivka Weinberg's 'Hazmat Theory'.