Historically, the title of “gentleman” was a birthright, used to identify men of a certain rank among English nobility. No doubt these men were expected to be well-mannered, but their status as gentlemen didn’t depend on how they acted. They were merely born into it.
Over time, what it meant to be a gentleman began to change. The title began to be applied to any well-educated man of prosperity. Gentlemen no longer had to be born into a social class, men could work their way to “gentleman-ship” by achieving worldly success.