In Netflix film Turning Point: Generation 9/11, the lives of people forever impacted by the terrorist attack in 2001 are explored

Twenty-five years on, memory is giving way to history. Soon the US will cross the point where half its population were born after 11 September 2001 or were too young to remember the day that terrorists crashed planes into the World Trade Center in New York, the Pentagon in northern Virginia and a field in Shanksville, Pennsylvania.

“When I do that math, I get to the bomb at Hiroshima – that’s how distant it is,” says Brian Knappenberger, 56, director of a new Netflix documentary, Turning Point: Generation 9/11. “When we talk about the second world war, for our generation it seemed like a long time ago but, for the current generation of 20-year-olds, that’s how long ago it was.”