Celts are part of the large cultural and linguistic Indo-European family. Their languages are related to those of the Greeks, the Romans, and most of the peoples of Europe (including English), Iran, and the Indian subcontinent. As noted earlier, it is generally thought that all these languages have roots in an ancient Proto-Indo-European language. There are indications, as well, of a deeply inherited common culture that includes such mythological themes as the Great Mother, the sacred twins, a warrior father-god, cattle stealing, an almost ritualistic heroic life pattern, the hero as monster slayer, tripartization, and creative sacrifice.