Percy Florence Shelley Bysshe Shelley, his namesake, and his wife author Mary Shelley. His elder siblings, consisting of a premature girl who died at few weeks old and a brother and a sister who died in childhood left him as the only surviving child as his mother suffered a miscarriage in 1822. His parents lived in Italy for several years, until his father drowned off Livorno, whereupon his mother moved back to England with him. Mary Shelley never remarried; Percy Florence had no further siblings. He joined Harrow School in 1832, and went up to Trinity College, Cambridge in October 1837. Shelley inherited
Percy Bysshe Shelley daughter of Roger Bysshe. Their son Timothy Shelley of Fen Place (born c.1700) married widow Johanna Plum from New York City. Timothy and Johanna were the great-grandparents of Percy. Percy was born to Sir Timothy Shelley (7 September 175324 April 1844) and his wife Elizabeth Pilfold following their marriage in October 1791. His father was son and heir to Sir Bysshe Shelley, 1st Baronet of Castle Goring (21 June 17316 January 1815) by his wife Mary Catherine Michell (d.7November 1760). His mother was daughter of Charles Pilfold of Effingham. Through his paternal grandmother, Percy was a great-grandson to Reverend Theobald