(CNN) A Nobel Prize-winning American scientist and DNA pioneer has been stripped of his honorary titles at the laboratory he once led after repeating racist comments in a documentary.

James Watson, who helped discover the double-helix structure of DNA alongside Francis Crick in the 1950s based on the work of British chemist Rosalind Franklin , said in a PBS film that genes cause a difference in intelligence between white and black people in IQ tests.

The 90-year-old's comments were labeled "reprehensible" by the Cold Spring Harbor Laboratory (CSHL) on New York's Long Island, where Watson had been the director from 1968 to 1993.

The laboratory said it "unequivocally rejects the unsubstantiated and reckless personal opinions Dr. James D. Watson expressed," noting the statements were "reprehensible [and] unsupported by science."

"The Laboratory condemns the misuse of science to justify prejudice," its statement added.