The world's largest gathering of twins took place this weekend in Twinsburg, Ohio.

More than 2,000 sets of twins and multiples took part in the event, which started in 1976.

The gathering provides entertainment, food, a twins' parade, music, and contests for the "most alike" and "least alike".

The city of Twinsburg was founded in 1819 by the twins Moses and Aaron Wilcox.

They were identical twins who were also business partners. The Wilcoxes married two sisters, had the same number of children and died of the same ailment a few hours apart.

At the festival, 10 teams of researchers study the pool of twins available.

Identical twins have 100% matching DNA, offering scientists the opportunity to compare between genetically identical people.

The University of Virginia is focusing on marriages, family and relationships.

At the festival, the researchers say they can compare "apples and apples", and try to establish, for example, why is one identical twin is happy but the other is not.

Meanwhile, Pittsburgh's Carlow University is studying how genetics affect our behaviour online.

How much time does each twin spend on social networks or shopping online? How many times they have been scammed? Is it nature or nurture?

Produced by Anna Bressanin, Camera by Chris Eadicicco