The man, 23, who cannot be named for legal reasons, sexually abused his brother and two cousins, one of them a girl aged just eight.
Garda Sgt Joe Keeley told Letterkenny Circuit Court in Co Donegal the offences came to light in February 2011 when a cousin using the man’s mobile phone saw explicit texts in his ‘sent message’ box.
The officer said the alarm was raised, social services were informed and Gardai called into investigate.
The man’s 11-year-old cousin was subsequently interviewed by specially-trained officers and he had spoken about weekly sex attacks, followed by payments of €30 or €40 and threats if he told anyone.
The victim’s eight-year-old sister – the girl who was abused four years earlier – also told of sickening sexual assaults which she had been enduring in 2011.
Sgt Keeley said the man bought the girl an ice lolly before assaulting her and threatened to hit her if she told anyone.
The paedophile’s brother revealed he had been sexually assaulted, but the abuse had stopped when he had turned 10.
The accused claimed in interviews that his eight-year-old cousin “knew all about sex.”
Desmond Murphy, SC, defending, told Judge John O’Hagan “The HSE was informed and the defendant was sent to Roscommon for a course but because of cutbacks in funding, he fell through the cracks.”
The accused, he said, would then go on to carry out further abuse of not just the girl, but the two boys as well between July 2007 and February 2011.
He said the paedophile had no moral guidelines and even said he was “evil.”
“The banality of evil took over – once he committed one assault, the rest followed,” said Mr Murphy.
Since being caught he had lived a simple life watching soap operas and following his favorite team, Man Utd, on television.
Judge O’Hagan said the accused had “stolen the innocence” of his victims and was a menace to society.
“He’s got something in his genes that if he can groom somebody he will do that,” said the judge.
Mr Murphy said his client would not survive in prison because of his youthful looks.
“He is a menace to his family and he could be a menace to society. He is 23 but he looks 12.”
The Judge jailed him for five years on each of the 25 counts, suspending the last two years of the concurrent sentence and ordered him to be kept on the sex offenders register indefinitely.