One of ten children, her siblings include Anne, wife of Francis Lovell, 1st Viscount Lovell; Margery, who married Sir Marmaduke Constable; Joan, a nun; Elizabeth Fitzhugh (grandmother to Queen Catherine Parr), who married Sir William Parr and then Sir Nicholas Vaux; and Richard, 6th Baron FitzHugh who married Hon.
[2] Her maternal grandparents were Richard Neville, 5th Earl of Salisbury and Lady Alice Montague, 5th Countess of Salisbury, suo jure, only daughter and heiress of Thomas Montacute, 4th Earl of Salisbury and Lady Eleanor Holland.
Through her grandfather, the Earl of Salisbury, she was a niece of Richard Neville, 16th Earl of Warwick (known in history as "Warwick, the Kingmaker"), a grandniece of Cecily Neville, Duchess of York (mother of King Edward IV and King Richard III) and a great-grandniece of King Henry IV.
At about the age of seventeen, Alice was married to Sir John Fiennes on 19 November 1466 at her home in Ravensworth, Yorkshire, England.
After her marriage she lived at Herstmonceux Castle in East Sussex, about 300 miles (500 km) away from her family and home.