What makes a Gentleman?

For those of you who enjoyed my entry about Michelle Obama's outfits and the ensueing discussion with Pastorius in the comment section, The Evil Style Queen's above question may be an interesting read, although she has got no nostrum as a reply:

To summarize, a "good" family" and education helps, as does dress-sense, a tall and slim physique and - even more - a clean-cut face and apparent intelligence. There are, however, clowns from old and "good" families, intelligent, good-looking men who do not, or not quite, make it, as there are well-dressed yobs. At the end of the day, I don't have an answer to my own question.

Here.