The boy, who cannot be named because of his age, was convicted after a trial at King’s Lynn Crown Court last week. The court heard that he harboured a hatred of women, had a fascination with serial killers and had planned to target others in the attack at Thorpe St Andrew School, near Norwich, on 11 March.
Speaking exclusively to the BBC, the boy’s father, referred to as John, said he did not want to absolve his son but said online material and “a culture of violence and horror” had influenced him. He apologised to the 15-year-old victim, who spent a night in hospital but was not seriously injured, and to her family.
John said the family had been “normal” before the attack, with his son shy but kind and thoughtful. As a teenager, he began spending more time alone, but John saw nothing concerning. However, after the attack police found that the boy had searched the internet for material on mass shootings and serial killers, including on the night before the attack. John said he had “no idea” about those searches and was shocked and devastated.
The boy’s notes, discovered at the family home, detailed plans for a wider attack and listed misanthropy, misogyny, suicide and bullying as motives. John said reading the notes made him feel “physically sick” and described his son as “a different person” who had emerged from what he was watching or seeing online.
John said his son told him his interest in extreme violence began after he saw a clip on TikTok from the TV drama Dexter, about a vigilante serial killer. “Once you watch one thing like that, the algorithm, of course, feeds you more of the same content,” he said. He called for tighter regulations, asking: “Is there enough being spent on this kind of thing?”
The father acknowledged parallels with the storyline of Netflix drama Adolescence, which explores the impact of social media and misogynist influencers on teenage boys. He said the show prompted a conversation with his son about “the manosphere and those sort of toxic influencers”.
Notes written by the boy expressed a hatred of women and he had researched Elliot Rodger, described to jurors as an early influence on incel and manosphere culture. But John said his son had never shown evidence of misogyny at home.
The family believed the boy was dealing with mental health issues before the attack, having wanted to self-harm and attempted suicide. John urged other parents to be “a bit intrusive” and to have proper conversations with their children.
A government spokesman said its thoughts were with everyone affected, and it was committed to ensuring all children were safe from radicalisation and threats online, pointing to the Prevent anti-terrorism scheme and the Online Safety Act.