Conceptual development and biology education research have shown that design teleology and psychological essentialism are obstacles in understanding biology, for instance in the case of evolution. In the context of genetics, these obstacles can be described as genetic teleology and genetic essentialism, respectively. In this chapter, we discuss previous research on these obstacles, and (re)define them. Genetic essentialism has been studied empirically mostly in the context of social psychology. Genetic teleology has not been defined as such and the related studies are limited, therefore we define this construct anew. We also present results from our study, in which we developed a questionnaire with 10 teleology items and 10 essentialism items in the context of genetics, which was administered to 396 high-school students, from October 2017 to May 2018. Our results showed that, in the context of genetics, teleological and essentialist conceptions are common among high-school students, and that the former, but not the latter, decrease with the age. Teachers might therefore rely on the teaching of natural selection to discuss and address teleological conceptions. Regarding essentialism, it seems that it has to be discussed and addressed explicitly, perhaps more than what is currently done.