October 7th: The Day Identical Twins Invaded Sweden

On this day in 1977, a research experiment involving the relationship between identical twins' human behaviour and the environment was launched. Ninety sets of identical twins journeyed to Felixstowe in Sweden for 'a brief shopping trip', although many of the siblings just considered it as a fun excursion, rather than part of a scientific investigation.

Do you know the "who's who?" of identical twins?

   Part of the study involved the twins dressing in the same clothes, just to confuse matters further. The ninety sets of twins ranged in ages from 11 to 80 years old, and had congregated in Felixstowe from all other parts of Sweden. The study was conducted by the Swedish Twin Register, who monitor them closely; and today over 70,000 twin pairs have been recorded between the years 1886 and 1990, which instigated a large volume of further investigations and interest. What do you think? Are twins completely influenced by environmental or external factors; or is it a genetic, innate factor that affects their behaviour?