The issue focused on the study of the 60-year-old study. "The study is all but complete, and the study is not even over," one of the researchers, study co-author Dr. Paul L. Alkema, of the University of California, San Francisco, said in a recent statement.

The study is "already out of date," said Dr. David H. Adesnik, a medical geneticist at the University of Washington, who was not involved in the study