Nature, Published online: 15 January 2025; doi:10.1038/d41586-024-04143-1A brain structure called the amygdala, and its connections with another region, the prefrontal cortex, shape peoples experiences and social interactions. The discovery of a key molecular mechanism that controls the development of these structures uncovers principles about how cortico-amygdala circuits form, and shows how this connectivity might be altered in neuropsychiatric disorders.