Castilla inherited the position of dean of Toledo on the death of his father in 1545. Castilla was of Jewish blood, and this became a major issue for him in 1547, when
Juan Martínez Silíceo the
archbishop of Toledo, passed a statute of
cleanliness of blood, excluding from ecclesiastical office and benefices anyone with a trace of Jewish lineage over four generations. Therefore, Castilla developed an obsession for genealogy, working tirelessly to prove his family's links to Spain's medieval kings. ==Patron of the arts==