Tadea of Austria illegitimate daughter of Charles V, Holy Roman Emperor, and Orsolina della Penna (b. 1523) Parents Orsolina della Penna Charles V Children Siblings Philip II of Spain John of Austria Juana de Austria y Xériga Juan Austria y Portugal Margaret of Parma Infante Fernando of Austria Joanna of Austria, Princess of Portugal Maria of Austria, Holy Roman Empress Isabel of Castile