A Nobel prize-winning scientist who helped discover DNA's double helix structure has been stripped of his honorary titles for repeating an "unsubstantiated and reckless" suggestion that genes make black people less intelligent.

Key points: James Watson said genes were responsible for a difference between races on IQ tests

James Watson said genes were responsible for a difference between races on IQ tests The Cold Spring Harbor Laboratory said it condemned "the misuse of science to justify prejudice"

The Cold Spring Harbor Laboratory said it condemned "the misuse of science to justify prejudice" The scientist lost his job in 2007 for making similar comments about race and intelligence

In an interview aired on US television earlier this month, James Watson — who won the Nobel in 1962 for his role in discovering DNA's double helix structure — said genes were responsible for a difference between black and white people on IQ tests.

He went on to say his views about intelligence and race had not changed since 2007, when he told a magazine that he was "inherently gloomy about the prospect of Africa" because "all our social policies are based on the fact that their intelligence is the same as ours — where all the testing says not really".

Cold Spring Harbor Laboratory (CSHL), which terminated Dr Watson's status as chancellor following those comments more than a decade ago, said his most recent statements "effectively reverse the written apology and retraction" he made in 2007.

In a statement, CSHL said in light of Dr Watson's views the laboratory had taken "additional steps" against Dr Watson, including revoking his honorary titles of chancellor emeritus, Oliver R. Grace professor emeritus, and honorary trustee.

"Dr Watson's statements are reprehensible, unsupported by science, and in no way represent the views of CSHL," it said.

"The laboratory condemns the misuse of science to justify prejudice.

"The statements he made in the documentary are completely and utterly incompatible with our mission, values and policies, and require the severing of any remaining vestiges of his involvement."

Dr Watson had long been associated with the laboratory, becoming its director in 1968, its president in 1994 and its chancellor 10 years later.

In 1962 Dr Watson shared the Nobel prize with collaborator Francis Crick and scientist Maurice Wilkins for discovering in 1953 that DNA was a double helix, shaped like a long, gently twisting ladder.

The breakthrough was key to determining how genetic material works, and the double helix became a widely recognised symbol of science.

He sold his Nobel prize medal in 2014 for $5.68m, telling media at the time he had been ostracised by the scientific community for his 2007 comments.

AP/ABC