The observation that few women reach the highest positions in science prompts the question of whether they are discriminated against. This column shows that at the French Institute of Physics at CNRS, one of Europe’s largest public research organisation, differences in research productivity account entirely for the average gender gap in the promotion from junior to senior positions. This finding does not contradict the observation that other promotion factors – such as family characteristics, mentoring, professional networks, and research responsibilities – have different impacts on female and male researchers.