Despite scientific evidence suggesting close phylogenetic relationship between chimpanzees and humans, the inclusion of these apes in the genus Homo is controversial. Several tools have been used to analyse this issue such as fossils, molecular clock and genome. This work intended to understand the biology teachers' conceptions about the humans' and chimpanzee's position. It was carried out in three countries with contrasting secularism conditions: Argentina, Brazil and Uruguay. Teachers were asked to answer to the BIOHEAD-CITIZEN project question: 'The Chimpanzee should be included in the genus Homo, notably because 98.5% of its DNA is identical to that of Homo sapiens'. Results were analysed within the KVP model framework and the Barbour's four categories of relationship between science knowledge and religion. Most questioned teachers (80%) of the three countries rejected the idea of including the chimpanzee in the genus Homo (86% of Argentinians, 71% of Brazilians and 71% Uruguayans), suggesting the conception of human beings having a special position in relation to other animal species. This study also indicates that the training of biology teachers needs to be analysed in the three countries to understand how teachers-to-be are being trained and evaluate their knowledge regarding molecular biology, phylogeny and evolution.