According to HISTORY OF HOMEOPATHY AND ITS INSTITUTIONS IN AMERICA, James Daniel Parker was born in Sandusky on September 2, 1876 to James Daniel and Sarah Gurley Parker. Mrs. Sarah Gurley Parker was the granddaughter of the pioneer Methodist preacher Rev. William Gurley.
James Daniel Parker graduated from the Cleveland Homeopathic College in 1900. Usually known as "J.D.," Dr. J. D. Parker practiced medicine in Sandusky from 1950 until 1955. He was also the father of two physicians, Dr. Watson D. Parker and Dr. Lester Parker. In Dr. Watson Parker's obituary, which appeared in the January 24, 2004 issue of the Toledo Blade, a Parker descendant stated that Dr. Watson Parker told stories of accompanying his father, Dr. J.D. Parker, on home visits to sick patients in Erie County, traveleing by horse and buggy.
In 1900, James Daniel Parker married Florence Glenn Day. An article in the August 29, 1900 issue of the Sandusky Morning Star reported that "one of the prettiest home weddings of the season" had taken place that day. The couple was wed at the home of the bride's mother. Miss Harriet Day, the bride's sister, was her bridesmaid, and the best man was Leroy Parker, a cousin to James Daniel Parker.
The couple had two daughters and three sons. During the summer months, the Parker family spent time at their cottage on Lake Erie in Mitiwanga.
On October 21, 1965, Dr. J. D. Parker passed away. Dr. Parker had been a member of the Erie County Medical Society, the Ohio and American Medical Associations, and Trinity Methodist Church. Private burial services were held at Oakland Cemetery, where Dr. Parker was buried next to his wife, who had died in 1946. An obituary for Dr. J. D. Parker was carried in the October 22, 1965 issue of the Sandusky Register.