Robert Penlington was born on December 2, 1915 to Thomas and Caroline Penlington, who lived in St Davids. Robert was the youngest of three children. His mother and the three children were listed on a passenger manifest of the SS Haverford which sailed from Liverpool, England in October 1920. She was listed as having citizenship in Great Briton, while the three children held US citizenship. Robert was nicknamed "Penny".
Robert graduated from Tredyffrin Easttown High School in 1934. His yearbook states:
“If you like Scotch jokes stop in Room 5 at noon and hear Penny tell some of his famous ones. Your laughter will be sure to mingle with ours when you join his appreciative audience. Wimpy obliges in another way, too – he’s our money lender.”
Robert married Martha in 1941 and they began their life together in Berwyn.