Mental disorders are under strong negative selection, although some appear to give a fitness benefit to siblings. This is hypotheses has long been trod out, so it is good to see in a large population sample that it doesn’t apply across the board.
- Power, R. A. (2012). Fecundity of Patients With Schizophrenia, Autism, Bipolar Disorder, Depression, Anorexia Nervosa, or Substance Abuse vs Their Unaffected Sibling. Archives of General Psychiatry