Children were suspects in almost one in five sex crimes detected by gardai in 2018.
A new report also shows 98pc of all sexual offences were carried out by males.
The figures were released by the Central Statistics Office (CSO) as part of its study into victims of serious crime last year, as well as suspected offenders for murder, sex crimes and assaults in 2018.
In 2019, males made up 82pc of homicide victims, while more than four in five victims of sexual violence were women.
Figures for 2018 show a person under the age of 18 was a suspected offender in 84 sexual offences, meaning almost 20pc of suspects for that crime group were children, while just 2pc were female.
Of the sex crimes reported last year, 24pc happened more than 10 years ago, with 833 victims who reported historic sexual abuse being children at the time of the alleged offences.
Dublin Rape Crisis Centre (DRCC) chief executive Noeline Blackwell said barriers remain to reporting but the organisation has noted an increased trend in reporting recent abuse.
"The CSO figures show a clear trend - that more offences happened within a year of reporting, and about a quarter of all reports related to abuse which took place 10 or more years ago," she said.
"This trend is in line with what we see in Dublin Rape Crisis Centre.
"While serious barriers remain to reporting - people blaming themselves when they shouldn't, or not wanting to report people they know, sometimes intimately - our own experience is there is an increasing trend towards reporting recent abuse."
Ms Blackwell said it was "in the wider society interest that when crimes happen, they are properly investigated and prosecuted, particularly in an area of crime which is vastly under-reported in comparison to other crime".
It is the first time there have been statistics provided on suspect offenders, identified as a person issued with a sanction such as a charge, summons or caution.
CSO statistician Sam Scriven said the figures "provide detail on the age and gender of both victims and suspected offenders of serious crimes reported to gardai".