The story of the British twin brothers Alex and Marcus Lewis in the documentary “Tell Me Who I Am” might have been concocted by the novelist Ian McEwan in one of his more unforgiving moods. Indeed, for the sake of the brothers themselves, one wishes their story were a fiction.

Alex was in his late teens when a motorcycle accident wiped out his memory, except for one thing: he recognized and knew his twin Marcus. He didn’t know his sprawling house, his odd parents, his nice girlfriend, anything else. He relied on Marcus, who reconstructed his past for him. Or rather, invented a past for him, removed from a horrific reality .