William was eight years of age when he became the heir to the thrown (Bio.com). William was the son of Robert I, duke of Normandy, his mistress Herleva (they called her Arletta), A tanner’s daughter from the town of Falaise (Bio.com). The duke designated William as his heir to the thrown. (Bio.com) William was of Viking origin (Bio.com). Though he grew up in Normandy and spoke with a delicate French accent (Bio.com).