Can’t guarantee that it will be the same for everyone who sees this film but this writer went through stages of amazement, joy, sadness only for anger to be the lasting emotion.

It is a remarkable film that unravels the extremes that some will go to in the name of science but also delves into the profound psychological effects it had on the three brothers as they tried to establish a relationship.

Starting in 1980 two complete strangers – Robert Shafran and Edward Galland – discover they are identical twins and reunited. The local media naturally report on this through which David Kellman realises that he is their brother. They had been separated at birth and sent to quite different families both in background and social status.

It’s an overwhelmingly happy occasion when the brothers are reunited, after 19 years. They are catapulted into the limelight with interviews on big name talks shows, feted by the media and engulfed by celebrity culture they dive headlong into its privileges and indulgences. Even appearing (briefly) in a Madonna film. Who wouldn’t turn down the offers they received?!

The parents, happy as they are with the reunions, have concerns and start to investigate the reasons for their boys’ separation. Starting with the agency they – and an investigative journalist who took an interest in the story - begin to track through complex web of complicity between government, academia and social services. The reason was to get to the root of fundamental questions of human behaviour regarding the questions of nature versus nurture.

There’s a jovial, almost comedy routine vibe to the brothers’ reunion at the start of the film as Robert and David recall the circumstances of their reunion and their instant celebrity status. As the glitter started to settle, they decided to go into business together and then there’s a marked change in tone as things take a downturn as it dawns on the trio that while they blood related, to all intents and purposes are little more than strangers.

There’s a palpable gap in the interviewees and it doesn’t take great powers of deduction to know why as the story is related and the brothers describe their sibling rifts and mental health problems.

There’s a grim underlay too as the nature of the experiments are revealed and the sociopathic outlook of those involved with them. The families are Jewish and there’s a justifiable correlation between what the boys were put through and the Nazis activities with twins. It’s not and doesn’t need to be overstated and Tim Wardle is appropriately sensitive.

The power of this film is that the viewer is never really ahead of brothers so a certain tension maintained as the truth is slowly revealed and the sheer scale of what has been going on is uncovered. It’s skilfully done and there’s no sense of exploitation of either the interviewees or the viewer.

It’s a grotesque, heart-breaking story of abuse and manipulation which had a profound effect of almost everyone concerned, with terrible human costs. The results of the experiments? Well some of the information is being released after relentless pressure but much is still sealed, not to be released until 2066.