Nobel Prize-winning American scientist James Watson, who helped discover DNA, has been shorn of honorary titles after repeating widely criticized comments about race in recent PBS documentary American Masters: Decoding Watson.

In 2007, research institution Cold Spring Harbor Laboratory removed Watson as chancellor after he told UK newspaper the Sunday Times 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, whereas all the testing says, not really”. He also said that while he wished races were equal, “people who have to deal with black employees find this not true.”

Watson apologized at the time but in the recently aired documentary he said his views had not changed. “Not at all,” he said in the PBS film. “I would like for them to have changed, that there be new knowledge that says that your nurture is much more important than nature. But I haven’t seen any knowledge. And there’s a difference on the average between blacks and whites on IQ tests. I would say the difference is, it’s genetic.”

The respected Cold Spring Harbor Laboratory has now said it is revoking Watson’s honorary titles, which include chancellor emeritus, Oliver R Grace professor emeritus, and honorary trustee, following the remarks which it described as “unsubstantiated and reckless.”

Dr Watson shared the Nobel in 1962 with Maurice Wilkins and Francis Crick for their 1953 discovery of the DNA’s double helix structure. The PBS documentary, which debuted on January 2, explores Watson’s life, achievements and controversies.

The 90-year-old scientist is currently in a nursing home recovering from a car accident and according to the BBC is said to have “very minimal” awareness of his surroundings. In an interview with the Associated Press, Watson’s son said the statements “might make him out to be a bigot and discriminatory” but that was not true.