Aggressive Discipline

From BPS comes a report of a new study:

Harsh discipline makes aggressive children worse

Parents should avoid harsh, combative ways of disciplining their aggressive children. That's according to psychologists whose new research shows that harsh parenting makes children more aggressive in the long run.

But, as often is the case with such research, there's a hitch:

A weakness in the research, acknowledged by the authors, is that all their measures were from mothers' self-report. One implication of this is that the observed associations could simply come from the fact that mothers who use more aggressive discipline are more likely to report their children's future behaviour as aggressive.

A weakness indeed. Moreover, as Judith Rich Harris is fond of pointing out, there's an enormous amount of scholarly literature purporting to show how parents affect children, but most of it misses the fact that 1) children's own behavior influences how their parents treat them, and 2) parents and children typically share the same genes, background, and environment, which means that their similar behavior could spring from something else (i.e., it wouldn't be that the children are just little lumps of clay being molded solely by their parents).