Because this is a technical article with nonstandard jargon, I'm going to state the most important piece of tacit knowledge that I know psychology professionals have but do not communicate to laymen (I personally came across it somewhere when reading the complete works of Eric Berne, but I can't recall exactly where).

Any apparent disorder in a person or persons has to be decomposed into the innate parts that existed prior to birth and the environmental experiences that happened afterwards as a prerequisite for any kind of theorising to give useful results instead of noise. They call this the diathesis-stress model and it's easily overlooked.