A new study found that spanking toddlers makes for more aggressive kindergartners.
As ABC News reports, three-year-olds who are spanked are more likely to bully, hit and engage in destructive or aggressive behavior.
The article quotes experts who say it's a simple case of modeling behavior: Your kids imitate your actions for better or worse. Digging down to the neurological level, between two and three years old is the time when the hippocampus is undergoing a growth spurt. Among other things, the hippocampus processes memories before they go into deep storage. In the memory store, they act as a sort of data bank that lets the brain compare stimuli coming in through the senses to previous experience in order to react appropriately.
So, it may be as simple as, "Anger? Hit!" Or, the spanking may have made the hypothalamus/pituitary/adrenal system, which reacts to stress, more reactive, leading to a stronger and more violent response.