I agree that the (seemingly) simple gesture of smiling makes a lasting impact on those around you- ESPECIALLY during early childhood. I think of how four year old me viewed my grandparents. One set of grandparents were always laughing, smiling and showing warmth and affection in non-verbal ways. The other set of grandparents were often stoic, unsmiling and my memories of them were cold and harsh. Upon reflection, both sets of grandparents had similar rules, expectations, verbal communication styles, but one was delivered with a warm voice and gentle face expression and the other was delivered in a way that four year old me perceived as scary and uncomfortable.