Douglas Sheffield, née Howard, was the oldest daughter of William Howard, 1st Baron Howard of Effingham, Surrey, and his wife, Margaret Gamage. Her date of birth has been a source of debate among historians. However, Simon Adams has argued that the dates of 1542 and 1543 are the most likely due to her being seventeen upon her marriage in 1560. Her older brother was Charles Howard, 2nd Baron of Effingham and 1st Earl of Nottingham. Charles was a successful English statesman and Lord High Admiral under Elizabeth I and James I. Commander of the English forces, he was hugely influential during the Armada period and was renowned for having been a significant figure in the naval defence against Spanish invasion during the 1590s. Douglas was part of a distinguished and notorious noble family that had been instrumental in court politics since the early sixteenth century. While her father held the title of baron, his half-brother was the Duke of Norfolk, William enjoyed a successful career under all four of the Tudor monarchs, and this favour ensured his daughter made a good marriage; Douglas married John Sheffield, 2nd Baron Sheffield. The couple had two surviving children: Edmund Sheffield, later 1st Earl of Mulgrave, and a daughter, Elizabeth, who married Thomas Butler, 10th Earl of Ormonde. The newly married couple were received well by the queen, who provided a wedding gift on 27th October 1560.