(Think your answer through. Avoid saying anything negative, like "My father was just a janitor or mother didnt work." Show pride in your background and heritage, even if you have come to regard it as very humble: "My father was a custodial supervisor, and my mother ran a busy home."
Be careful about overstating, too. Avoid an answer like "My father is the leading brain surgeon in the state and my mother is a retired Superior Court judge." In such cases, "My father is a surgeon and my mother is an attoney and former judge" positions you properly.)
My father is a _________________, and my mother is a ________________.