Using sweets as bait and claiming it was "just a bit of craic", Mickey McCarville groomed his young victims for a campaign of sexual abuse.
The farm labourer targeted them all over the land where he worked: in sheds, outhouses, in fields and on tractor rides.
Five victims wept during an emotional sentence hearing as McCarville (49) was jailed for more than 20 years for the rape of six children and molesting a seventh in the same family.
McCarville began abusing the first child in 1982 when the victim was aged 10.
The abuser was aged 15 himself and had begun working as a labourer on a family farm in the north of the country.
The sisters and brothers were aged as young as seven and 10 when the abuse began. The attacks continued for 18 years up to 1999, taking place in farm sheds, outhouses and fields.
The Monaghan native, with an address in Longfield, Lisboduff, Cootehill, Co Cavan, was charged with 187 counts of indecent assault and sexual assault of the seven children between 1982 and 1999. He pleaded guilty last December to 52 sample charges.
The seven victims have agreed that although they do not wish to waive their right to anonymity, they are happy for McCarville to be named.
McCarville's first victim was just 10 years old when he began sexually assaulting him. These attacks occurred up to three times a week at various locations including within the family home.
In 1983, he also began abusing the man's seven-year-old sister. He continued to rape her for five years. At the same time McCarville was anally raping a third brother, who was aged between 10 and 12.
Victim impacts statements for the seven adult siblings were read out during a lengthy sentence hearing at the Central Criminal Court.
Five of the victims read their own statements, breaking down in tears as they described the harrowing effects of the abuse.
The eldest child, now aged 45, said McCarville was "a master manipulator" who split the children apart in order to control them and get what he wanted. He described his utter shock and horror when he learned over the last two years that his four brothers and two sisters had been abused too.
"I was overpowered by an evil and disgusting man who spent his life manipulating me," he said.
He later added that he felt that "it's a miracle that we have all survived".
Many of the victims described how the sustained and regular abuse destroyed their childhood and has blighted their adulthood.
One brother described how in 1988 he ran to tell his mother after he saw McCarville molesting his brother in a farm shed.
"He caught me. I felt scared and confused. He told me if I told my mother, it would kill her," he said. McCarville then began grooming this child by buying him sweets and soon began abusing him and his brother together.
Mr Justice Patrick McCarthy said he struggled with whether McCarville should be handed down a life sentence as the offences were of the utmost seriousness, but he added that he should be given credit for his plea of guilty.
He sentenced him to 20 years in prison and ordered that he carry out five years' post-release supervision.
Mr Justice McCarthy said McCarville "must have been treated as a family member, at least in terms of day-to-day matters", adding this made the crimes more obnoxious.
He described them as being "a serious breach of trust".
Remy Farrell SC, defending, said that his client, who assists with his local church and GAA club, had instructed him to offer an apology to the victims.