limitation of AP to do with correlation not causation
Correlation not causation
Adorno and his colleagues measured an impressive range of variables and found many significant correlations between them
For instance, they found that authoritarianism was strongly correlated with measures of prejudice against minority groups
However, no matter how strong a correlation between two variables might be, it doesn't follow that one causes the other.
Therefore, Adorno could not claim that a harsh parenting style caused the development of an AP.