More than 17,500 boys aged 14 carry a knife or weapon in England and Wales, according to an official estimate from the Home Office.
The figure is in a report analysing “indicators of serious violence” on people born in 2000 and 2001.
The research found that an only child, or teenagers with four or more siblings, were more likely to be involved in serious violence.
Other factors included those who faced “child maltreatment”, and bullying.
The study published by the Home Office found about a third of those arming themselves had had weapons used against them.
They were also more likely to use drugs than those who did not use weapons.
It also concluded that ethnicity was “not significantly associated” with using or carrying a weapon.
The research was based on the Millennium Cohort Study (MCS) – a sample of 11,024 people.
Analysts examined their behaviour at the age of 13 to 15.
It said: “3.47% of the sample population reported weapon carrying/use and that 71.3% of these were male.
“As the MCS is a nationally representative survey, this can be scaled to the national population by multiplying by the number of 14-year-olds in England and Wales.”
It estimated 17,521 males in the population are likely to report weapon carrying or use at the age of 14.