Dr James Watson, the 1962 Nobel Prize winner for co-discovery of the DNA double helix. FILE PICTURE: SARAH BREZINSKY/AP

London - A scientist who won the Nobel Prize for his work on DNA has been stripped of honorary titles over his ‘racist’ theories on genetics.

James Watson, who shared his prize for his work at Cambridge with Francis Crick, has repeated his claim that black people are inherently less intelligent.

The American biologist, 90, said in a TV documentary shown this month that he stood by his views that ‘all our social policies are based on the fact that their intelligence is the same as ours – where all the testing says not really’.

He claimed the differences in intelligence between black and white people was borne out by their average scores in IQ tests. In his original remarks to a magazine in 2007, Dr Watson had added that while he hoped everyone was equal, ‘people who have to deal with black employees find this is not true’.

Last week he was removed from three honorary positions at the New York lab where he spent most of his career. The board of trustees at Cold Spring Harbor Laboratory on Long Island described the views of Dr Watson as reprehensible.

He and British biologist Dr Crick were awarded the Nobel Prize in Physiology or Medicine in 1962 for their discovery nine years earlier of the double helix structure of DNA, the molecules that carry all the genetic information determining how we grow, function and reproduce. The breakthrough was key to understanding the body’s genetic code.

In February 1953, a jubilant Dr Crick walked into The Eagle pub in Cambridge, the local for scientists at the University’s Cavendish Laboratory, and proclaimed he and Dr Watson had ‘found the secret of life’.

A blue plaque at the pub marks their discovery. Dr Crick died in 2004.

In a statement, Cold Spring Harbor Laboratory said it ‘unequivocally rejects the unsubstantiated and reckless personal opinions Dr Watson expressed on the subject of ethnicity and genetics’. It said it was revoking his titles as chancellor emeritus, professor emeritus and honorary trustee.

The lab added: ‘Dr Watson’s statements are reprehensible, unsupported by science, and in no way represent the views of CSHL, its trustees, faculty, staff, or students. The laboratory condemns the misuse of science to justify prejudice.’

Dr Watson’s son Rufus said his father, who is in a nursing home following a car crash in October, was being made out to be a bigot, which was untrue.

‘They just represent his rather narrow interpretation of genetic destiny,’ he said.

Daily Mail