Peter Mock was born circa 1766, likely in Maryland, to german immigrant Peter Mock and his wife Elizabeth. As a young boy, he moved with his family to Bedford County, Pennsylvania where they took up farming. In the mid to late 1790s, Peter married Catherine Garn, the daughter of another local farmer and german immigrant, John Garn and his wife Margaret Syen.
Peter farmed nearly 200 acres in St. Clair. Together, he and Catherine raised eleven children: Elizabeth, Frances (Franny), Christian, Peter, Margaret, Catherine, Thomas, Joseph, Rachel, Frederick C., and Barbara.
Peter passed away in 1826. Catherine survived him by thirty years, passing away in 1856.