They have refused to reveal who his father is - but the chubby cheeks could have given the game away.
With their round faces, Elton John and his son Zachary looked uncannily similar during a trip to Venice yesterday.
And the five-month-old’s big blue eyes put onlookers in mind of Sir Elton’s 1982 hit Blue Eyes.
Like father? Elton John and son Zachary in Venice
Family outing: Elton John with David Furnish and their son Zachary
Zachary’s other father, filmmaker David Furnish, joined the pair on their visit to the Venice Biennale, a contemporary art exhibition. The proud parents cuddled and cooed over their new addition as they travelled across the city.
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The little boy, who was born to a surrogate mother on Christmas Day last year, will grow up to call Sir Elton ‘Daddy’ and Furnish ‘Papa’.
But the couple do not yet know who the child’s biological father is. Furnish said: ‘Neither of us care. He’s our child. The important thing is that he’s healthy and happy and loved.
Out and about: Sir Elton John with son Zachary in Venice
The couple became parents through a surrogate, who gave birth to Zachary in a California hospital on Christmas Day last year.
During the conception process, the mixing of their semen specimens was allowed - a process which is currently banned in the UK - before being used to fertilise a previously chosen egg.
In January, filmmaker David, 48, told OK! magazine: '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.'
Lucky men: Sir Elton John and David Furnish with their son Zachary at Marco Polo Airport in VeniceMeanwhile, the couple, who tied the knot with a civil partnership in 2005, have made the shortlist for Celebrity Dad of the Year, the first gay couple ever to be nominated.
They said they were 'thrilled' by the news.
Other nominees this year include Wayne Rooney and David Beckham, Take That star singer Gary Barlow and Jonathan Ross.
Sleepy boy: Sir Elton John and David Furnish's son ZacharyLast year's winner, Peter Andre - who has five-year-old Junior and three-year-old Princess Tiaamii with ex-wife Katie Price - is also nominated again.
Elton has previously pledged to make Zachary a grounded child despite his parents' fame and riches.
The Rocket Man singer said: 'I so value my own childhood now, and we want to give Zachary - as much as we possibly can - the same thing. A solid old-fashioned childhood, if you like.'
