For all my disagreement with the late Sen. Kennedy, I once sat behind him in the underground transport of the Senate. He was talking with others and I noticed he always stood and let the others go in front of him and held the door open for them. No, they weren't in the service class, but it was still gracious, a sign of having been raised decently, at least in the area of manners.
I agree. Somethings are learned just by observation growing up. No matter what character they display later on - those good qualities do linger. Holding the door, giving others the seat, allowing others to go first was what they did. Not as a show but it came natural because it was a part of them by what they witnessed early on.