My son had been living abroad for four years. When he finally came home, I was waiting at the airport, emotional and excited. A tall bearded man walked toward me smiling, and I moved aside because I thought he was trying to pass.
It was my son. I genuinely didn't recognize him for several seconds. He laughed, but I went home and cried privately because it hit me how much of his adulthood I had missed. He thinks it's a funny family story. For me, it still hurts.