In the book 'The Boy in the Striped Pyjamas,' what are the ages of Hitler and Bruno's father?

In The Boy With the Striped Pyjamas, Bruno and his family move to "Out-With" (what Bruno calls Auschwitz) in the early 1940s.  They needed to move because "the Fury had big things in mind" for Bruno's father ("the Fury" is what Bruno calls Hitler, instead of the Führer).  Bruno's father is given a promotion to be the commandant of "Out-With."

According to the author of the book, Bruno's father is not specifically based on a historic figure in Nazi Germany.  The real life commandant of Auschwitz for many years was a man named Rudolf Hoess.  His family also lived at Auschwitz.  These facts make it likely the story is based on Rudolf Hoess and his family.  Considering this, that would make Bruno's father a man in his early forties.  In the early 1940s, Adolf Hitler was in his early fifties.