A massive global genetics study is reshaping how we understand mental illness—and why diagnoses so often pile up. By analyzing genetic data from more than six million people, researchers uncovered deep genetic connections across 14 psychiatric conditions, showing that many disorders share common biological roots. Instead of existing in isolation, these conditions fall into five overlapping families, helping explain why depression, anxiety, PTSD, bipolar disorder, schizophrenia, and substance use disorders so frequently occur together.