 The paper from which this quote is taken was meant to be a summary of a longer paper, also published in 1931 (Wright 1986: 88). In the longer paper (1931a), Wright specifies that the random sampling is of gametes. (Gametes are cells that fuse together during fertilization, such as an egg and a sperm). So, even though Wright (1931a) notes that the Hagedoorns had “urged the importance of such random fixation as a factor in evolution”, and states that Fisher (1922b) had analyzed the issue, has he changed the subject to be random sampling of gametes rather than of “parents” (i.e., organisms)? In short, no: Wright (1932 and elsewhere) makes it clear that he considers drift to encompass both random sampling of gametes and random sampling of organisms. In other words, he has expanded the phenomena that the concept of drift is meant to cover from that discussed by Gulick, the Hagedoorns, and Fisher. But Wright’s 1932 paper also emphasized what would become a persistent confusion between drift and inbreeding; both inbreeding and drift are more significant in small populations, so it can become easy to conflate them. But you can have random sampling of parents (say, through a population split) without inbreeding, and inbreeding without random sampling of parents. That alone shows that drift and inbreeding are not the same. So, not all of the expansions of drift were productive ones.