This chapter constitutes a philosophical examination of the long contest between nature and nurture in the areas of concern of Behavioral Biology, Ethology and Psychology. The paper considers the roles of the notions of innateness and acquisition in the causal production of behavior. While there seems to be broad agreement to the effect that the dichotomy between what is innate and what is learned is misguided and obsolete, this essay concerns the epistemological and ontological reasons why neither nativism nor environmentalism constitute heuristically fruitful views in accounting for the origination of behavior. The chapter starts off by providing a historical presentation of some of the cornerstones of both innatism and environmentalism in the development of classical Ethology and Behaviorist Psychology. It then proceeds to examine how the debate between innatism and environmentalism has subsequently been dismantled by more recent approaches in the Behavioral Sciences. Finally, the author ends up with some philosophical comments concerning the empirical and conceptual pitfalls of both traditions and the inadequateness of the dichotomous framework of the dispute when addressing the causal channels by which the development of behavioral patterns takes place.