lawrence's parents were unitarians, but he became anglican and was confirmed as a member of st. paul's episcopal church in boston in 1842. he met and married sarah elizabeth appleton (1822–1891) at the church. sarah was a daughter of u.s. representative william appleton and mary ann appleton (née cutler). his mother was a relative of samuel appleton, a trustee of massachusetts general hospital and president of the young men's benevolent society.