One of the science education objective, based on relationships between science, technology, society and environment (STSE) is, to form citizens capable on evaluating and taking decisions about the scientific advances impact on society and environment. In a two-way perspective, understand relationships between STSE, provides a vision of science as a human construction and therefore fallible, changeable and not neutral. In this study, we present some results from a comparative study on the influence of ethical conceptions of the nature of science, in two groups of future biology teachers, one from Brazil and, another one from Portugal. For data collection we constructed an attitude scale of Likert-type, which was validated mathematically and semantically. Results shows strong influence of social values, as in transgenic products, where the students’ ideas varied according to the ethical discussions more present in each country.