There is a growing body of research on variability in the early development of biological knowledge. Most of the studies focus on the variability related to culture and direct exposure to nature, however, there is also data suggesting that parental input plays an important role. In children’s first years of life, parents play a key role in scaffolding development. It is therefore very important to provide a detailed account of how parents contribute to children’s understanding of living things, and how they convey biological knowledge through everyday conversations. The present article provides a review of the literature on variability in biological knowledge and parent-child conversations about biological kinds. It also presents original data from parent-child interactions while viewing picture books. Eighteen parent-child dyads who differed in the level of parental expertise within biology, talked while viewing books containing 24 photographs of animals and plants. The speech analysis specified labeling, perceptual and conceptual descriptions, relational, and mentalistic talk. Parents also completed a questionnaire on the child’s interests. The results showed that biology expert families produced more content overall, and a higher proportion of relational content than lay families. The findings help elucidate the specific role parents have in shaping children’s early biological understanding. In particular, I discuss the role of relational language in shaping children's ontological commitments