His son Ronald H. Adler is an opera director .
His son Ronald H. Adler has been artistic director at the Bavarian State Opera ( 2001 -- 08 ) and the Berlin State Opera ( 2008 -- 11 ) .
His son Ronald H. Adler is an opera director and has been artistic director at the Bavarian State Opera ( 2001 -- 08 ) and the Berlin State Opera ( 2008 -- 11 ) .