From Shakespeare’s Hamlet, Act 1, scene 4:
HORATIO:     Is it a custom?
HAMLET:      Ay, marry, is’t:
But to my mind, though I am native here
And to the manner born, it is a custom
More honour’d in the breach than the observance.

When Hamlet described himself as “to the manner born”, what he meant was that he was destined to be suited to the custom in question by virtue of his birth (“I am native here”). Shakespeare wrote Hamlet in about 1600, and he probably coined (or at least first popularized) this phrase. Note, however, that there is no suggestion of high class or nobility in the original meaning of the expression; at that time, “to the manner born” could just as easily refer to someone of lowly status accustomed to the practices of his family business, or indeed to anyone destined by dint of their birth to certain thoughts or practices common to their circumstances. Thomas Hardy, writing about his hero the sheep-farmer Gabriel Oak in Far From the Madding Crowd (1874), noted that “if occasion demanded he could do or think a thing with as mercurial a dash as can the men of towns who are more to the manner born.”

Class or status did creep in, however, when a similar expression, “to the manor born”, entered standard English in the mid-19th century.  It means more or less the same as Shakespeare’s phrase, but the emphasis is on one’s nobility — rather than simply one’s birth — making you destined for a certain suitability, usually to the comforts or advantages of a privileged class. Whereas manner denoted simply customs or habit, its homophone manor signifies a mansion or estate associated with the wealthy or upper classes. The second phrase seems to have become more common and more standard than the original, at least in colloquial usage (and of course they’re more or less identical in spoken form), with the result that the two expressions have become virtually indistinguishable in their meaning; both now convey the sense of loftiness that was inherent only in the younger, newer expression.

Linguists and etymologists have long argued about the relationship between the two sayings: was the second one introduced as a spin-off of the first by accident or by design? Was it a deliberate play on words, with someone changing the spelling of “manner” to “manor” in order to introduce an extra element to the phrase, or even just as a pun? Or was this an example of what modern linguists call an “eggcorn”: an erroneous misspelling that comes into its own and eventually assumes its own slightly different meaning?

An eggcorn differs from a pun in that it begins as an error; much like its cousins the mondegreen and the malapropism, an eggcorn arises when someone hears and perceives a spoken word as either a homophone or a combination of words that sound similar, and the resulting misspelling assumes its own — often slightly eccentric — meaning. A classic eggcorn is the phrase “duck tape”, which sounds just like “duct tape” but can easily be — and evidently was — misheard at some point, taking on a new life of its own with its inadvertent new spelling.

To the Manor Born was a popular BBC sitcom broadcast in 1979. That it had such high ratings and was so apparent in the English culture of the time might help explain why this version of the phrase has became more standard in the vernacular than Shakespeare’s original — perhaps even more so in England than in the US?

Well, that’s my excuse, because I have to admit it: I thought that this was the original and only spelling and meaning of the phrase (and I watched the TV show). I was unaware that I’ve been using a pun or an eggcorn all these years, when I could have been quoting Shakespeare …