Caitlin Clarke is the eldest daughter of Dr. Charles Clarke, a metro Pittsburgh physician and World War II veteran. He was still working as an internist, despite his remarkable age, until he retired in 2014. Ms. Clarke's mother, Cecilia, assisted him in his work before she passed away on May 4th, 2006.
Ms. Clarke has four younger sisters, all very accomplished. At the time of this article (2007):
TorieClarke was a private consultant, whose former office brought the family into the spotlight.
There is more about Ms. Clarke's sisters (esp. Torie) on this February 2003 article from the Pittsburgh Post-Gazette. Torie herself gets a page of her own on this site.
Ms. Clarke also has several paternal relatives. I corresponded with one of them, a Baltimore-area painter with three children, from time to time until some time after Ms. Clarke's death.
Ms. Clarke was married to Michael McLaughlin, an Oxford alumnus and philosophy professor from Lock Haven University. I recently learned that he and Ms. Clarke divorced in 1985; that Mr. McLaughlin has since left Lock Haven; and both were back on amiable terms when Ms. Clarke passed away.
The Clarke family has made more recent history. Ms. Clarke's youngest sister, Victoria
Torie Clarke, was mad assistant secretary for public relations at the U.S. Department of Defense on May 2001. She held the post until her resignation on June 2003. During her time in office she comported herself well during the attack on the Pentagon in 2001 and the subsequent wars in Afghanistan and Iraq. Opinions on her behavior otherwise is not appropriate for this site.
For a long time I believed that Caitlin Clarke was a descendant of Thomas Shields Clarke, a shipping magnate who was one of Pittsburgh's earliest business barons.
At first I wasn't completely sure and didn't mention this; then I decided to add a page on T.S. Clarke, with a conjecture, that Ms. Clarke is a leaf on this venerable tree. The page is largely an excerpt from a history of Pittsburgh from the late nineteenth century.
I have since been enlightened by my correspondent that in fact Ms. Clarke's ancestors immigrated from the village of South Molton in southwestern England in the 1880's. Ms. Clarke is not a descendant, and I have updated the T.S. Clarke page accordingly.