73-year-old Mick Jagger has sired his eighth child, and first with 29-year-old ballerina Melanie Hamrick, who he started dating in 2014. The couple announced that they were expecting a child back in July, and today he has finally been born, per The Evening Standard. The Rolling Stones frontman now has eight children with five different mothers, five grandchildren, and one great granddaughter. The Jagger dynasty continues…