The ways in which children and adolescents become interested in science have been well studied. However, little is known from a lifespan perspective about how this process continues from childhood through adulthood. This cross-national study builds an understanding of doctoral students in the sciences in the Chile and the United States and how they choose to pursue careers in the life sciences from childhood to adulthood. Fifteen Chilean and 15 U.S. doctoral students were interviewed using the life story approach. The qualitative analysis indicates that the main difference between the two groups when pursuing science across their lifespans was their valuation of and experience with different learning approaches, with 'collectivist' approaches being more typical for the Chilean students and 'individualist' approaches for the U.S. students. On the other hand, the principal similarities between the two groups were related to participants' experiences and perceptions of science at each life stage: 'playing science' as children, 'studying science' as adolescents, 'doing science' as young adults and undergrads, and 'labouring in science' and 'practising science' as professionals and doctoral students. Implications for pedagogical practice and planning for science teaching and teacher training are addressed.