The study is the largest in the world so far and was performed in collaboration with the Queen Mary University of London. More than 7,600 Swedish twins (men and women) aged 20-47 years responded to a 2005 - 2006 survey of health, behaviour, and sexuality. Seven percent of the twins had ever had a same-sex sexual partner.

"The results show, that familial and public attitudes might be less important for our sexual behaviour than previously suggested", says Associate Professor Niklas Långström, one of the involved researchers. "Instead, genetic factors and the individual's unique biological and social environments play the biggest role. Studies like this are needed to improve our basic understanding of sexuality and to inform the public debate."

The conclusions apply equally well to why people only have sex with persons of the opposite sex as to why we have sex with same-sex partners. However, the conclusions are more difficult to transfer to countries where non-heterosexual behaviour remains prohibited.

Overall, the environment shared by twins (including familial and societal attitudes) explained 0-17% of the choice of sexual partner, genetic factors 18-39% and the unique environment 61-66%. The individual's unique environment includes, for example, circumstances during pregnancy and childbirth, physical and psychological trauma (e.g., accidents, violence, and disease), peer groups, and sexual experiences.

If borne out experimentally, his work could help explode Moore’s Law and could revolutionize computing technology.

Moore’s Law predicts that the number of transistors that can be economically placed on an integrated circuit will double about every two years. But by 2020, Moore’s Law is expected to hit a brick wall, as manufacturing costs rise and transistors shrink beyond the reach of the laws of classical physics.

A solution lies in the fabled molecular switch. If molecules could replace the current generation of transistors, you could fit more than a trillion switches onto a centimeter-square chip. In 1999, a team of researchers at Yale University published a description of the first such switch, but scientists have been unable to replicate their discovery or explain how it worked. Now, Pati believes he and his team may have found the mechanism behind the switch.

Applying quantum physics, he and his group developed a computer model of an organometallic molecule firmly bound between two gold electrodes. Then he turned on the juice.

As the laws of physics would suggest, the current increased along with the voltage, until it rose to a miniscule 142 microamps. Then suddenly, and counterintuitively, it dropped, a mysterious phenomenon known as negative differential resistance, or NDR. Pati was astonished at what his analysis of the NDR revealed.

Up until the 142-microamp tipping point, the molecule’s cloud of electrons had been whizzing about the nucleus in equilibrium, like planets orbiting the sun. But under the bombardment of the higher voltage, that steady state fell apart, and the electrons were forced into a different equilibrium, a process known as “quantum phase transition.”

“I never thought this would happen,” Pati said. “I was really excited to see this beautiful result.”

Why is this important? A molecule that can exhibit two different phases when subjected to electric fields has promise as a switch: one phase is the “zero” and the other the “one,” which form the foundation of digital electronics.

Scientists have analyzed a "light echo" from the original explosion of Cassiopeia A, the youngest known supernova in our own Milky Way galaxy.

The explosion occurred around 1680 -- just yesterday, in stellar terms.

The scientists observed an infrared spectrum of radiation that suggests Cassiopeia A was a type IIb supernova and was birthed from the collapse of a red supergiant star.