My two year old ds just learned how to give kisses! He has been kissing me "goodbye" when either he or I am leaving the house, for about a week now! Today he kissed my dw for the first time, and he also kissed one of his preschool teachers! I don't know if it is a particularly affectionate act for him, but he loves routine...and it seems this is becoming part of his "goodbye" routine. I love it.