Identical triplets their secret world.

This documentary visits at the realm of four sets of identical triplets. Doris, Gladys and Alice are 83. They describe what it's been like growing up as part of a set of three. Katy, Libby and Anne work as photographic models; Craig, Ed and Scott share a house and are in band 'The Noise Next Door'; Lorna, Leanne and Lindsay see themselves as one person split into two. The programme focuses on the latter two sets of triplets and covers areas such as sibling rivalry which is fierce with triplets and how hard it is for an identical threesome to both assert their identity and cope with being apart. Tests are carried out to see what differences EDR readings show in triplets' brains, a psychologist assesses how their personalities differ and a further test attempts to detect the presence of a sixth sense between triplets.