John, 56, said: "It's been uplifting. Especially when he smiles at me and seems contented in my arms. He's given the house and renewed spirit and purpose. He's brought us a new beginning and his presence has brought joy to all the people who have wanted the best for us."
However, the couple – who also have a 10-year-old daughter Ella Bleu – admitted they feel "blessed" to have finally had another child after trying for three years to conceive.
Kelly, 48, explained: "We tried for three years and feel blessed that it finally happened. It's one of the most fulfilling things a person can experience in life and I have had the joy of experiencing it with three amazing children. Being a mother makes me the happiest."
Baby Benjamin – who was born by Cesarean section at Florida's Munroe Regional Medical Center – is also a constant reminder of Jett in terms of his looks.
John added to Britain's Hello! magazine: "Like Jett, he definitely looks like his daddy, but every day he changes and often we can see his mother in him."