I have a question about The Boy in the striped Pj's ... whats the meaning behind the story and why does the dad lie to his own family?

I kinda think that its about not keeping secrets from those close to you cause jk the kid ran into the gas chamber cause he had no clue what it was and the dad most likely lies to his family cause he doesnt want to traumatuse the sh*t out of his kid by telling him that their killing a sh*t loas of people very day