Scott Alexander refutes Stephen Skolnick's theory that schizophrenia is caused by gut microbes rather than genetics, showing why the evidence better supports schizophrenia being a complex genetic neurodevelopmental disorder. Longer summary

Scott Alexander responds to Stephen Skolnick's theory that schizophrenia is caused by gut microbes rather than genetics. He systematically dismantles Skolnick's arguments by showing that twin concordance rates are exactly what we'd expect from a genetic condition, that microbiological inheritance patterns don't match schizophrenia inheritance patterns, and that the gut bacteria evidence cited was likely caused by antipsychotic medication rather than being causative. He concludes by explaining why schizophrenia is best understood as a complex neurodevelopmental disorder with multiple contributing factors rather than having a single cause. Shorter summary

Scott Alexander uses simulations to explain why seemingly counterintuitive arguments against the genetic basis of schizophrenia are misleading. Longer summary

Scott Alexander discusses two seemingly counterintuitive arguments against the genetic basis of schizophrenia and explains why they're not as compelling as they might appear. He uses a simplified simulation to demonstrate how a highly heritable disorder can have low twin concordance rates and why eliminating affected individuals doesn't significantly reduce prevalence in the next generation. The post aims to clarify common misunderstandings about polygenic disorders and their inheritance patterns. Shorter summary