He has a younger brother, Nicholas Cowell; three half-brothers, John, Tony, and Michael Cowell; and a half-sister, June Cowell.
Dia mempunyai seorang adik kandung laki-laki, Nicholas Cowell; tiga saudara tiri laki-laki, John, Tony, dan Michael Cowell; dan seorang saudari tiri perempuan, June Cowell.