DS asked when he was about 7. He asked DH when I wasn't home, but I believe DH blew it. I came home to the tears and sobs of DS.
When I asked DM about Santa, she told me, "If you are asking about a fat man in a red suit and flying reindeer, then no that is not real, however she went on to tell me all about the "real" Santa--St. Nicholas, and all he did. After telling me about St. Nicholas she talked about the magic of Christmas. People giving to those in need, Christmas spirit, etc. She said it was because that time of year is magical and grace from heaven is felt more, etc. She ended the talk with saying even though Santa is not real, she believes that the spirit of St. Nicholas is among us. I came away with a even bigger sense of awe.
DD is 7 and I think we have at the most 3 more years of "Santa" at my house. I have informed DH that I will be giving the Santa talk, he can teach her to drive. LOL