Would Patrick Dempsey have become a successful actor if his name had been "Patrick Schlossnagle"?
Patrick Galen Dempsey was born in Lewiston, Maine, to William A. and Amanda M. Dempsey. His father died 9 June 1986, and his obituary appeared two days later in the Lewiston Sun Journal:
BUCKFIELD—William A. (Bill) Dempsey, 72, of Morrill Street, Buckfield, died Monday at Central Maine Medical Center, Lewiston. He was born 20 September 1913, at Marcus Hook, Pa., the son of John and Jane Devonshire Dempsey. He was a graduate of Rising Sun High School, Rising Sun, Md. Mr. Dempsey was married to the former Amanda Caisson and they had made their home in the Turner and Buckfield area since 1967. He was self-employed as a bar owner while living in Maryland and also was an insurance agent. He was a former member of Masonic Bodies and the Elks while in Rising Sun, Md. He is survived by his wife of Buckfield; two sons, Jack of Minneapolis, Minn., and Patrick of New York, N.Y.; two daughters, Mrs. Alice Dempsey of St. Petersburg, Fla., and Mrs. Mary Lagasse of Auburn; one sister, Geneveve Crothers of Conowingo, Md.; and four grandchildren.
But William was not born a Dempsey, and is not found under that name in either the 1920 or 1930 census. He is, though, found under the name William Schlossnagle, living with his mother Jane, step-father John W. Dempsey, and sister Genevieve G. Schlossnagle in Eighth Election District, Cecil County, Maryland, in 1930. We find him in 1920 living with his sister Genevieve in Oakwood, Cecil County, Maryland, in the household of their grandparents Benjamin Franklin and Lydia Jennette "Nettie" (Mattson) Devonshire (a bit more on Benjamin's ancestry here). This obituary for William's nephew confirms that his sister's maiden name was Gertrude Genevieve Schlossnagle.
So who was William and Genevieve's biological father? Their entries in the 1920 census say that he was born in Maryland, while the 1930 census gives his place of birth as Pennsylvania. Jane Devonshire was not yet married in 1910, and she did not live with her parents and children in 1920. (The 1930 census suggests that she and John W. Dempsey were off marrying at about that time, but I have not found them honeymooning anywhere in the 1920 census.) It is very likely that the children were fathered by one of the sons of Adam Schlossnagle (himself the son of Bavarian immigrants) and his wife Edith Friend, who lived in Marcus Hook, Pennsylvania, in 1910. Among their many sons, I think the most likely sperm donor is Asa B. Schlossnagle—born September 1892 while the family was living in Garrett County, Maryland, and in 1910 living unmarried with his parents in Marcus Hook.
Asa's five brothers all registered for the World War I draft as residents of Delaware County, Pennsylvania, but Asa did not. We know that William A. Schlossnagle was born September 1913 in Delaware County, while his sister was born in Maryland in December 1915. I think it is likely that Asa B. Schlossnagle was their father, and that he died around 1915-17. I would propose that he died in 1915 before the birth of his second child, and that his wife Jane returned to Cecil County, Maryland, to live with her parents and bear her daughter, but that would be utter speculation unfit for publication.
Update: And here is the proof: The marriage record of Asa Schlossnagle and Jane Devonshire.
Corrections and additions are welcome in the comments.