This day in history | 1977 Invasion of Swedish identical twins

Ninety sets of Swedish identical twins have travelled to Felixstowe for a brief shopping trip.
The twins are taking part in studies by researchers from the Karolinska Institutet in Stockholm.
The scientists are investigating links between the environment and human behaviour.
But participants are viewing the excursion as a form of light relief. As one twin put it, they have come across “just for fun”.
As the twins disembarked from their ship, the Tor Scandinavia, each pair was confusingly dressed in matching outfits.
It is hoped the sets of siblings might find something different to wear when they spend their money in the local shops and boutiques.
The visit to Felixstowe is the brainchild of the ship’s captain, Sune Dahlström, also a twin.
He claims his inspiration to charter the ‘twins cruise’ came from an encounter a few years ago with two identical twin sisters riding identical twin horses.
“For me it’s very strange indeed to see so many people who are identical – although I’m used to it myself, it’s very strange you know,” he said.
Aged between 11 and 80 the sets of twins come from all parts of Sweden and most live apart from each other.
But today they are reunited, and looking to spend.

Courtesy BBC News

In context

The project was one of the largest of its kind. It was conducted through the Swedish Twin Register, which is one of the most comprehensive resources for clinical, epidemiological and genetic studies.
Today over 70 thousand twin pairs born between 1886 and 1990 are on the register, from which over 370 papers have been published.
Monozygotic (identical) twins come from one fertilized egg (zygote) which divides and develops into more than one embryo.
Because they are genetically identical, differences between them are typically the result of environmental or external influences.
Twin studies are therefore very useful in determining whether a condition is genetic, environmental, or both.