Kate Middleton ethnicity is White - English.
Catherine, Duchess of Cambridge (née Catherine "Kate" Elizabeth Middleton; born 9 January 1982) is the wife of Prince William, Duke of Cambridge. Through marriage, she is also titled Princess Willian, Countess of Strathearn and Lady Carrickfergus. Catherine grew up in Chapel Row at Bucklebury, a village near Newbury, Berkshire,[1] and studied in Scotland at the University of St Andrews, where she met Prince William in 2001. They started a romantic relationship that continued until a break-up lasting for several months in 2007. However, they continued to be friends and rekindled their relationship later that year.