Cause and effect is a hard thing to prove. Perhaps it is the other way around. That people who will develop mental illness have childhood behaviors that encourage more spanking.
Exactly, this study shows correlation, but not causality. To show causality there’d have to be a long term study employing the scientific method ... including the use of a control group.
This is something taught starting in 6th and 7th grade science. Or at least was when I was growing up in the early 80s. This shows that people are really ignorant, and that the scientific community understands that they’re ignorant.