Sir Elton John has revealed he wants to have another baby - so his son has support when he is teased about not having a mother.
The pop superstar, 65, said he and partner David Furnish had talked about the prospect of Zachary being targeted over his untraditional family set-up before they fathered him with a surrogate mother 15 months ago.
In an interview with Guardian, Sir Elton said it was inevitable that the toddler would face pressure over his family life as he is growing up.
"I think it's difficult to be an only child, and to be an only child of someone famous," he said.
"I want him to have a sibling so he has someone to be with. I know when he goes to school there's going to be an awful lot of pressure, and I know he's going to have people saying, 'You don't have a mummy'.
"It's going to happen. We talked about it before we had him. I want someone to be at his side and back him up. We shall see."
The Rocket Man singer said the fact he was an only child of an unhappy marriage and spent a lot of time by himself listening to his parents argue was another reason why he wanted more children.
During the revealing interview, Sir Elton, who will perform at the Queen's Diamond Jubilee concert at Buckingham Palace tomorrow night, also revealed he worries about Zachary being spoilt by a global army-of well-wishers and friends.
He said: "At Christmas we bought him a swing for the garden and a little slide, and this was his Christmas present and his birthday present from us.
"But he had so many presents from other people throughout the world, which is touching, but we actually found it obscene."
The star, who has been know for his extravagant lifestyle, said they gave most of the gifts to charity.