John, 65, who is due to perform at the Queen's Diamond Jubilee Concert at Buckingham Palace on June 4, says the one-year-old will be spoilt by fans who send an obscene amount of presents for him, reported Daily Express.
"At Christmas we (David and I) bought him a swing for the garden and a little slide and this was his Christmas present and his birthday present from us.
"He had so many presents from other people throughout the world, which is touching, but we actually found it obscene. I said 'This is shocking. Four hours we've been opening presents. It is crazy'," he said.
Their son, Zachary Jackson Levon Furnish-John, was born on Christmas Day in 2010 to a surrogate mother.
John will perform 'I'm Still Standing', 'Your Song' and 'Crocodile Rock' as part of his show for the Diamond Jubilee celebrations of Queen Elizabeth.