“When a child hits a child, we call it aggression.
When a child hits an adult, we call it hostility.
When an adult hits an adult, we call it assault.
When an adult hits a child, we call it discipline.” 

• Punishment focuses a child on the "consequences" he is suffering, rather than on the consequences of his behavior to someone else, so it makes him more self-centered.
• Punishment makes a child feel like he's a bad person, which is always a self-fulfilling prophecy, so he's more likely to repeat the bad behavior.
• The most salient lesson of punishment is to avoid it in the future by sneaking and lying to escape detection, so punishment fosters dishonesty.
• Because kids invariably consider punishment unfair, it teaches kids that might makes right and abuse of power is ok -- which makes kids less likely to make moral choices.
• Punishment--yes, even timeouts--erode our relationship with our child, so that he isn't as invested in pleasing us.  And the more disconnected he feels from us, the worse his behavior.
• Because punishment doesn't help a child with the emotions that drove her to act out to begin with, those emotions just get stuffed down, only to pop up again later and cause a repeat of the misbehavior.
• Punishment makes a child feel wronged, and creates a "chip on the shoulder" so she's likely to resent making amends. 
• Punishment makes kids look out only for themselves and blame others, rather than caring about how their behavior affects others.
• Punishment creates an external locus of control -- the authority figure. The child actually comes to see the parent as responsible for making her behave, rather than taking responsibility for her behavior as her own choice.

         The most important tip, as always in parenting, is to manage yourself so you can stay calm.  Remember that the holidays are stressful for kids, and your kids depend on you not only to regulate their environment, but also to help them regulate their moods