I guess we were not perfect parents in this area. Most parents tell their kids about their daddy or mommy's job. We didn't. Why didn't we? My husband was a finance controller in a bank and it was rather difficult to explain that to our young child as would some people who have "normal" jobs as a teacher, or a doctor, or an engineer, etc. So we simply decided to delay the subject until our child mature a bit more to tell her. The only thing I told her was that daddy was a very busy man in the office.
One day, she was asked the question by a guest to our home : What does your daddy do for a living?
The 4-year-old little girl gave it a thought and said, "Well, he is a very busy man in the office.... He dust some and he mop some."
She was actually thinking of our housekeeper doing chores. Since she had no clue of her daddy's job, she could only use what our maid did as a reference.