Sex/gender differences in the brain are not trivial-A commentary on Eliot et al. (2021)

In this commentary to the comprehensive review by Eliot et al. (2021), we fully comply with rejecting the 'sexual dimorphism' concept in its extreme, binary form. However, we criticise the authors' extreme position and argue that sex/gender differences in the brain are far from being 'trivial' and 'unlikely to be meaningful'. Our key arguments refer to the importance of small effects which can have meaningful behavioural consequences, and to several non-binary sex/gender-related factors which might explain individual differences better than sex/gender per se and which have shown to play important roles as risk factors in the aetiology of many mental and neurodevelopmental disorders. We conclude that the biopsychosocial approach is key to understanding sex/gender differences in the brain better than we currently do.