The mother of a Briton who died fighting for Islamist terror group Al Shabaab has said she fears "no one is immune" to radicalisation.
Sally Evans, whose son Thomas Evans, 25, was among suspected extremists killed in an attack on an army camp in northern Kenya in June, said families should speak out against extremist ideology.
Mr Evans's younger brother Michael recently said he "hates" his sibling for the pain he put their mother through, while David Cameron has announced new measures to prevent extremism.
Mrs Evans, writing in The Times, said: "If a young man from High Wycombe who was raised in a secular household can be turned into a terrorist, then perhaps no one is immune. Radicalisation is not just a threat to the Muslim community but to all of us. And that is why we must fight against the Islamist ideology, even though at times it may seem as though we are losing the battle."
She said she did not oppose her son's conversion to Islam and hoped religion would "help settle his wayward teenage behaviour", but he became more hardline.
"I would come to learn, but unfortunately too late, that Thomas was not practising Islam; he was practising an ideology that hijacks an otherwise peaceful religion for its own jihadist ends," she said.
She added she would not "suffer in silence" and urged other families to speak out about the impact of radicalisation on their lives.
Thomas Evans contacted his family to say he had travelled to Somalia to join Al Shabaab in 2012 after leaving their home in Buckinghamshire. He had previously converted to Islam.
His mother and brother told earlier this year how they confirmed his death after finding a picture of his body online.
Al Shabaab, which is banned in the UK, is a Somalia-based group with links to al Qaida which has waged a violent campaign against the Somali transitional federal government for several years.
Up to 50 Britons are believed to have joined the organisation.