Open Image ModalOn the back of this news, here are our guesses... Other Possible Sons Of Frank SinatraHarry Connick, Jr.(01 of07)Open Image ModalMichael Bublé (02 of07)Open Image ModalJamie Cullum(03 of07)Open Image ModalKurt Elling(04 of07)Open Image ModalRod Stewart(05 of07)Open Image ModalRobbie Williams(06 of07)Open Image ModalBryan Ferry(07 of07)Open Image ModalSEE ALSO: Ronan Farrow 'Could Be Mia Farrow's Son'