The scientists who produced Dolly, the world's first cloned sheep, are at loggerheads over who deserves credit for the breakthrough.
The debate was ignited by an admission this week from Professor Ian Wilmut -- the scientist widely credited for the research -- that he did not create the animal after all.
Speaking at an employment tribunal in Edinburgh, Scotland, Wilmut said he did not develop the technology or conduct the experiments, and played only a supervisory role.
The birth of Dolly in July 1996 was regarded as a leap forward in cloning technology and triggered a surge of similar efforts to clone other animals.
The work was published in the journal Nature in 1997 and rapidly made Wilmut, who led the research group at the Roslin Institute, one of the most high-profile scientists in the world.
At the tribunal, in which one of Wilmut's colleagues, Prim Singh, alleges bullying, the scientist said he did not play a trivial role in the project to clone Dolly and coordinated the work, but added that 66 percent of the credit should go to Professor Keith Campbell, a co-author on the 1997 paper.
But researchers close to the project say the scientists involved still have major disagreements over who deserves credit for cloning Dolly.
According to one source, all the credit for the breakthrough should go to Campbell, who left the Roslin Institute shortly after the paper was published.
Bill Ritchie, a lab technician, still working at Roslin, said all the cloning lab work that led to Dolly was done by him and another technician, Karen Mycock, so the credit should be theirs.
"It's been an ongoing argument since it happened. Everyone has their own different set of facts," said one scientist.