Probably because Psychology is super individual und culturally dependent.
Nothing Psychologists ever "find out" generally applies, but just happens in their little circle und their circumstances in their time.
Nothing Psychologists ever "find out" generally applies, but just happens in their little circle und their circumstances in their time.
Hopefully the discourse is shifting, but a culture can be dysfunctional (like allowing first cousin or even worse double first cousin marriages, for example) for a very long time before it collapses.