Split at Birth: Twins Divided

In the 1960s, a well-respected adoption agency in New York deliberately split up infant twins and placed them in different families as part of a controversial study. The programme has had a seismic impact on many of their lives.

The BBC's Melissa Hogenboom has tracked down identical and fraternal twin participants, as well as one of the original researchers involved, to understand why the twins are still seeking answers about this intrusive experiment.