Frederick Younken Jr. was born on April 20, 1790 in Bucks County, PA, the son of Johannes "Frederick" and Maria Barbara (Dieter) Younkin. He is not to be confused with his younger half brother, Frederick F. Younkin, born in 1801.
Frederick Jr. married Elizabeth (?) and had nine offspring – Anna Margarethea Younkin, Matilda Younkin, Charles Younkin, Hannah Elizabeth Younkin, Nicholas Younkin, Henry H. Younkin, Mary Younkin, Sarah Younkin and Catharine Younkin.
Frederick Jr. was a millwright, living in Nickamixon Township. Tragically, he died accidentally at the age of 48 in Nickamixon Township in late October or early November 1838. The incident generated news coverage in the Nov. 21, 1838 edition of the Bucks County Intelligencer.
A century after his death, he was mentioned in the April 30, 1938 edition of the Younkin Family News Bulletin.