With heritability methodology researchers using twin studies, and during recent year also DNA studies, have claimed that heredity plays a crucial role in explaining social outcomes. Explaining what causes social outcomes is a strive to explain how reality is constituted, and is thus an ontological question. The purpose of this article is to examine the unspoken ontological assumptions in heritability studies from a critical realistic perspective. First I’ll explain the basics of the heritability methodology, the twin methodology and DNA studies that measure heritability, then I’ll describe the previous criticism of these studies. Thereafter I’ll argue that the heritability studies do not examine the actual causes of social events, but rather that the measures are driven by other underlying mechanisms, which thus are the ones possessing the generative power to influence social outcomes. Against this background, I argue that the studies commit the fallacy of misplaced concreteness and the epistemic fallacy. In conclusion, I argue that concrete social phenomena should be understood as an interplay between different generative mechanisms.