Sir Elton John and David Furnish have become parents to son Zachary Jackson Levon Furnish-John, the couple tells UsMagazine.com exclusively.The baby boy, who was born Dec. 25 in California via a surrogate, weighed 7 pounds, 15 ounces. "We are overwhelmed with happiness and joy at this very special moment," John and Furnish tell Us in a joint statement. "Zachary is healthy and doing really well, and we are very proud and happy parents." This is the first child for John, 62, and Furnish, 48. The couple married in 2005 after 12 years together.