A 21-year-old Belfast man allegedly raped his younger brother and sister, a court has been told.
He is also accused of abusing a cousin as part of a planned and premeditated series of sexual assaults on family members.
The alleged offences were committed over a four-year period when the defendant was himself as young as 12.
He appeared at Belfast Magistrates' Court on Wednesday charged with two counts of raping a child aged under 13.
The accused, who cannot be named for legal reasons, also faces counts of sexual activity with a child family member, and engaging in sexual activity in the presence of a child.
Police said the charges relate to dates between 2011 and 2015.
Opposing bail, a detective claimed the defendant could commit further offences if released.
"He is suspected of committing multiple sexual offences against children he has had access to, and a number of these offences have shown a high degree of premeditation and planning," the detective said.
During interviews the accused denied all of the allegations, but told police his memory may have been affected by taking drugs since the age of 11.
Concerns were also raised about a potential risk to his own safety if others living in the neighbourhood become aware of the charges.
Defence solicitor Damien Trainor said the case has led to "a massive rift" within the family.
"They have essentially turned their backs on him now," he told the court.
However, Mr Trainor argued that his client was only between 12 and 15 when the alleged offences were committed.
"At the time of these allegations he was a child in the eyes of the law," the lawyer said.
"He was so young that, even if convicted, he wouldn't have been able to go to the Young Offenders' Centre."
Granting bail to an address approved by police, District Judge George Conner stressed it must be at a location outside Belfast.
He also banned the accused from contacting any alleged victims.
But with the prosecution set to appeal the decision at the High Court, the defendant remains in custody.