“…Monozygotic twins, however, share much closer signatures, indicating some genotypic basis of olfactory identity (Romeyer et al, 1993b). Transmission of odors from the dam to the neonate, known as maternal labeling (Alexander, Stevens, & Bradley, 1989;Gubernick, 1981), is not critical for the initial establishment of maternal selectivity (Alexander et al, 1986;Poindron et al, 1988;Romeyer et al, 1993a). Nonetheless, it can contribute to the development of odor differences between neonates, for example, in young with initially very similar signatures (e.g., monozygotic twins; Romeyer et al, 1993b).…”