The 23-year-old, who cannot be named for legal reasons, 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 Feb 2011 when a cousin using the man’s mobile phone saw explicit texts in his sent messages list.
Sgt Keeley said the alarm was raised, social services were informed, and gardaí were called into investigate.
The man’s 11-year-old cousin was interviewed by specially trained officers and he revealed weekly sex attacks, followed by payments of €30 or €40 and threats if he told anybody.
This victim’s sister also told of sickening sexual assaults which she had been enduring in 2011.
Sgt Keeley said the man bought the girl an ice cream before assaulting her and threatened to hit her if she told anybody.
The paedophile’s brother also revealed he had been sexually assaulted, but the abuse had stopped when he had turned 10.
The paedophile claimed during interviews that his female 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 paedophile, he said, went on to further abuse not just the girl, but the two boys as well between July 2007 and Feb 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.
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 jail 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 for life.