"Emperor Maximilian I" (details from "Emperor Maximilian I") (see related A | B), 1502 Ambrogio de'Predis (1455-1508) Kunsthistorishes Museum, Vienna, Austria

Maximilian in other portraits had a "Habsburg" protruding or prominent lower lip, and in some, also a prominent chin or prognathia. His wife and mother of their son Felipe had normal facial features, as did Felipe. The son of Felipe and Juana of Castilla, Carlos I of Spain or Charles V of Austria, had mandibular overgrowth, prognathism, and an underbite of severe degree. The question is, how did this gene mutation reach or arose in Carlos I (see full discussion in the companion web-site Clinical Eye Openers (CEO).