Ben Needham would be 24 today - for his family the day is likely to bring the latest in a 20-year series of disappointments.
DNA results are expected later on a Romanian man being tested due to a likeness to missing Ben - however now it seems it's unlikely the two will show a match.
Sources close to the testing process tell me that Greek police sent them photos of birthmarks Ben had on his body and the man now being tested does not have at least one of them.
Ben was 21-months-old when he vanished from the island of Kos in 1991.
At the time he had a coffee coloured mark on his right knee and a red birthmark on the back of his neck. There is no sign of a mark on the neck of the man at the centre of this latest investigation.
The formal results are expected later - staff at the Institute of Neurology and Genetics who are carrying out the tests have been told they must continue to work until they get clarification, such is the importance of their task.
The sister of a child who went missing in Greece more than 20 years ago says she wants her own DNA to be tested against that of a little girl found in a Roma camp in the country in case the girl is related to her missing brother.
Sheffield boy Ben Needham was just 21 months old when he went missing on Greek holiday island Kos in 1991.
His sister Leighanna Needham, 20, never met Ben but said the discovery of the girl - called Maria - in the camp was welcome news for her family's fight for answers.
"I think that would be a brilliant thing to get our DNA out there, even if it's not actually Ben but any siblings or any children maybe of Ben [that are found] then that could hopefully lead us to him," she told Sky News.
Kerry Needham has returned home to Yorkshire after spending three weeks in Greece following up more tip-offs from the public about where her son might be.
Kerry's son Ben went missing from the Greek island of Kos in 1991 but the police search and the high-profile excavation at the farmhouse from where he disappeared, have thrust his case once more into the world spotlight.
She made the trip after new leads emerged in December, following an appeal on a live Greek show which specialises in tracing missing people. The programme showed clips from Calendar of Kerry's most testing times in the hunt for her son. She spoke to Calendar last night.