Ellen Cracknell was a Muggle woman and a member of the Umbridge family. She was married to a wizard named Orford Umbridge. The couple had two children together. The first was Dolores Umbridge. Their younger child, a son, was a squib. Although they were married for more than fifteen years, Ellen’s marriage to Orford was an unhappy one. Eventually, she cut ties with her husband and daughter, and took her squib son with her to return to ordinary Muggle life (Pm).
Voldemort, too, had a Muggle parent and a magical parent whose marriage did not last. -BB
Both Voldemort's and Umbridge's backgrounds are problematic for the views they come to hold on blood purity, and both are reminiscent of a widely held (although discredited) belief that Adolf Hitler had Jewish ancestry (source: Wikipedia). -BB