Simplify the following text for a Grade 7 native English-speaking person.
Original: All William IV 's legitimate children ( children with his wife ) died before he became king , so they were therefore styled as Prince\/Princess of Clarence with the style of Royal Highness .
Simplified: All legitimate issue of William IV were born , and died , before his accession to the throne . They were therefore styled as Prince\/Princess of Clarence with the style of Royal Highness .