\u201cThere are powerful methods for studying the genetic and environmental origins of individual differences, but not for studying the causes of average differences between groups,\u201d Dr. Plomin he writes in an afterword to be published this spring in the paperback edition of his book, \u201cBlueprint: How DNA Makes Us Who We Are.\u201d Whether Dr. Watson was aware of any of this science is unclear. In the film, he appears to have grown increasingly isolated. He mentions missing Francis Crick, his collaborator in the race to decipher the structure of DNA. \u201cWe liked each other,\u2019\u2019 Dr. Watson says of Dr. Crick. \u201cI couldn\u2019t get enough of him.\u2019\u2019 As history now knows, the duo was able to solve the puzzle in 1953, with their hallmark models of cardboard and metal only with the help of another scientist, Rosalind Franklin, whose X-ray photograph of the DNA molecule was shown to Dr. Watson without her permission. The tools of molecular biology unlocked by their discovery have since been used to trace humanity\u2019s prehistory, devise lifesaving therapies, and develop Crispr, a gene-editing technology that was used recently, and unethically, to alter the DNA of twin human embryos. And Dr. Watson became perhaps the most influential biologist of the second half of the 20th century. His textbook, \u201cMolecular Biology of the Gene,\u2019\u2019 helped define the new field. First in a laboratory at Harvard and then at Cold Spring Harbor, he trained a new generation of molecular biologists and used his star power to champion such projects as the first sequencing of the human genome. \u201cYou knew when you heard him that you were at the start of a revolution in understanding,\u2019\u2019 Nancy Hopkins, a biologist at the Massachusetts Institute of Technology who studied with Dr. Watson in the 1960s, says in \u201cDecoding Watson.\u2019\u2019 \u201cYou felt as if you were part of this tiny group of people who had seen the light.\u2019\u2019 Mr. Mannucci, the director and producer, was drawn to his subject by a certain similarity to \u201cthe King Lear story\u2019,\u2019 he said \u2014 \u201cthat this man was at the height of his powers and, through his own character flaws, was brought down.\u201d The film highlights Dr. Watson\u2019s penchant for provocation, exemplified by his candid 1968 memoir, \u201cThe Double Helix,\u201d of the race to decipher DNA\u2019s structure.