 One of two children, Joseph Clark was born in Philadelphia to Joseph Sill Clark Sr. and Kate Richardson Avery.His father, a longtime lawyer in the Germantown section of the city, was also a national tennis champion who won the 1885 U.S. National Championship in doubles with Dick Sears.His mother, whose family owned Avery Island in Louisiana, was the niece of Edmund McIlhenny, the inventor of Tabasco sauce.