In the genealogy of Jesus, there are ancestors who were not Jews by birth. Ruth, from Moab, and Rahab, a Canaanite, come to mind.
Actally, Ruth lived in Moab therefore she was called a Moabite...Ruth was an Israelite...you have Chinese who were born in America and are called Americans yet are Chinese. It is actually the same with Rahab, an Israelite.