Elton John and David Furnish's sons, Zachary Jackson Levon Furnish-John and Elijah Joseph Daniel Furnish-John, were born in California in 2010 and 2013. They have both contributed to the sperm specimens and, therefore, don't know who the biological father is. The surrogate mother carried both sons, and David is listed as the mother on the birth certificates to protect her identity. The children call Elton "Daddy" and David "Papa." Zachary's middle name, Levon, is inspired by an Elton John song. Elijah's middle name, Joseph, is inspired by the couple's rescue dog,…