Elton John's partner David Furnish says both of them "contributed" to the conception of their son Zachary, who was born to an unidentified surrogate mother on Christmas Day 2010.
The 63-year-old singer and Furnish, a 48-year-old Canadian filmmaker, appear with their new baby on the covers of Us Weekly and OK! magazines. Proceeds from the photos are set to go to charity.
When asked which of them is Zachary's biological father, Furnish said: "We both contributed. For the time being we don't have a clue. We look at him every day and at the moment he has Elton's nose and my hands," according to The Daily Mail, a UK newspaper.
John is registered as Zachary's father, while Furnish is named in the mother category on the baby's birth certificate, the newspaper said.
"Suddenly, at 2:15 a.m. on Christmas Day, we were woken up," John told OK! magazine. "They said, 'Quickly! The baby's coming!' We went in and stood behind the bed. Then the top of the head came out and David said, 'My God, there's the head!'"
"'Then he shot out like a rocket basically - so much so that the obstetrician sort of caught him!" he added. "It was so dramatic and exciting. We didn't have time to get emotional. This is a big change in our life. We have to see how we cope and adapt with one child before we even consider a second."
John and Furnish have been together since the 1990s and entered into a civil union in 2005.
The pair, one of the most high-profile gay couples in the world, tried to adopt an AIDS-infected orphan in Ukraine last year, but was rejected. Local laws say the age difference between an adoptive parent and a child must be 45 years or less and parents must be married. The European country also does not recognize John's union with Furnish as a legal marriage.