Artificial intelligence can differentiate between the brain patterns of boys and girls aged 9 to 10 years old according to their sex, and possibly their gender – but not everyone is convinced by the accuracy of the results. The prevalence of conditions such as pain, headache and heart disease differs between the sexes, but we know little about the neurological variations here or between genders, particularly among children. To learn more, Elvisha Dhamala at the Feinstein Institutes for Medical Research in New York and her colleagues analysed thousands of sets of magnetic resonance imaging (MRI) data from more than 4700 children, with a roughly even split between the sexes. The children were all aged 9 to 10 and are participating in the Adolescent Brain Cognitive Development project. Sex was defined according to someone's "anatomy, physiology, genetics and/or hormones at birth".