That study:
Thrawn first of all, a selection that small leaves a margin of error that is astronomical.
Secondly, they measured the amount of corporal punishment applied in family by the amount their mothers were spanking the kids during the auditions. What about the mothers who were shy to hit the kids during the interview and beat the crap out of them later? Lol.
What about the chance that those kids who needed to be slapped during the audition were hyperactive, less social and generally more stupid than the average child and therefore needed tougher discipline? In fact I believe that was exactly the case. The parents were used to slap the bonehead prats so they did it even during supervision unconciously.
So, if we look at that kind of studies with even a tiny bit of criticism, we found out that the study had no base to begin with, too many unknown factors.
In fact, despite endless amounts of theories, nobody still knows exactly how a human being develops, gets his habits, IQ and possible homocidal impulses.
There simply are too many effecting factors and comparisons are made impossible since there aren't groups of people who would have exactly the same backgrounds, level of intelligence etc. Humans genetic variations cancel it alone, from syblings the other may become a genius and the other remain average or vice versa. How are you going to compare a group of families if you can't even compare the methods used within a single one with the results in hand?
