But for Australians,the question about whether to name him is different. This man was born,raised and radicalised in Australia. Are we adequately interrogating his formative experiences and how they may have shaped his behaviour?

Labor senator Kristina Keneally said last week:"The fact that it was an Australian who committed the Christchurch shootings should have been a wake-up call to Australia at the time it happened."

On Wednesday,Home Affairs Minister Peter Dutton committed to an inquiry into right-wing extremism after several weeks of pressure from Labor.

This came as police arrested an 18-year-old man near the NSW/Victoria border and charged him with terrorism-related offences,understood to relate to far-right extremism.

Tarrant's parents split up when he was between seven and nine years old,the New Zealand inquiry reported. His mother,Sharon Tarrant,told the Australian Federal Police her children were traumatised by the separation and other events,including the loss of their family home in a fire and the death of their grandfather. She said her son's personality changed after the separation,with him becoming clingy,anxious and not socialising well with others.

In his early teenage years,he put on weight and was bullied by other students. Then at around age 16 or 17,while his father was dying of asbestos-related lung cancer,Tarrant lost 52 kilograms by exercising compulsively at gyms and following a strict diet.

After the break-up,Tarrant and his sister Lauren initially lived with their mother and later with their mother and her new partner. But that relationship was violent,with the new partner assaulting Sharon Tarrant and the children. First Lauren and then Tarrant went to live with their father.

Joanne Orlando,a researcher in technology,education,children and digital culture at the Western Sydney University,said the fact his mother's partner was abusive was another warning sign.

"We know growing up in a violent environment contributes to our understanding that violence is an everyday kind of scenario and does desensitise a person to acting in a violent way,"she said.

Throughout his childhood and teenage years,Tarrant was left to his own devices with technology. The report describes how he was interested in video games from the age of six or seven,especially massively multiplayer online role-playing games,other online role-playing games and first-person shooter games. The inquiry found that as a child he had unsupervised access to the internet from a computer in his bedroom and he also spent much of his free time at school accessing the internet on school computers.

Tarrant's immersion in far-right internet groups as an adult is well reported. But in 2017,he told his mother that when he was 14 he had started using the 4chan internet message board,which is notorious as a hotbed of white supremacy and far-right conspiracy theories.

Dr Orlando said it was"safe to say that being immersed in those kinds of sites long term would have desensitised him to racism or racist comments"."He was in an echo chamber in those kinds of environments,where everyone is saying that kind of thing so it kind of normalises it and makes it very acceptable,"she said.

While many children use the internet independently without these problems emerging,she advised parents to keep an eye on what their children were viewing online and talk to them about it.

Dr Orlando warned online hate - such as racist comments and gender put-downs - was increasing between children and teenagers since the advent of COVID-19.