"While severe neurodevelopmental disorders (NDDs) caused by penetrant de novo mutations approximate Mendelian models of causality, Mendelian causal logic has been seen as inapplicable to common mental disorders for decades. I sometimes think that it is criminal that Mendel is taught in school without even a whiff of quantitative genetics to balance it."

https://www.psychiatrymargins.com/p/a-note-from-hyman-on-the-genetic