The use of possessive pronouns in phrases like "I don't know my geography" or "He certainly knows his Star Wars"

Question

There's a rather peculiar use of possessive pronouns. In my experience, it normally occurs in the context of referring to someone's familiarity with a particular subject (or lack therof), e.g.

You clearly know your art history.

or

What can I say, I don't know my Shakespeare.

or even

He knows his Claret from his Beaujolais.

Even though the meaning of this construction is nearly always clear from the context, I would like to see a "formalized" explanation of this sort of usage— one that ideally would provide answers to the following questions:

1. What is the difference between saying You clearly know art history and You clearly know your art history? What sort of meaning does the your in the latter sentence serve to convey?

2. I think I've mostly seen this usage in British English. Is it a specifically British way of speaking or is it used in other varities of English, too?

3. Outside of referring to someone's degree of knowledge in a particular area, are there any other contexts that this usage can occur in? In other words, what other verbs besides know can be used with a personal pronoun in this way? (I think I've come across phrases like he loves his food, but I'm not too sure).

Answer 1

Although I can't give a "formalized" explanation, I wanted to look at using the possessive with personal nouns in the same way that you've done in your examples. Imagine the following situations and example utterances:

Situation 1: Your wife, Sarah, is suspected of giving aid to known terrorist organizations.

I know my Sarah. She would never be involved with something like that.

Situation 2: Your son, John, was offered a college scholarship an account of his high marks in high school.

That's my Johnny. He's always been such a bright pupil.

In this usage, the possessive is used for providing emphasis -- the object is something that the possessor is intimately familiar with. Notice that you can make the same statements without the possessive:

"I know Sarah. She would never be involved with something like that."

The statement is the same but the fact that "Sarah" is an object which the possesor is intimately familiar with is minimized. The semantic difference is small, but I feel it might be similar to emphasizing certain words in particular sentences. (e.g. compare "Are you wearing that dress to the banquet?" to "Are you wearing that dress to the banquet?")

She knows her Star Wars.

She knows her world history.

She knows her calculus.

For these formulations, I'm tempted to interpret the possessive exactly as above (used for emphasis), but one can't ignore the particular phrase "to know one's X" as idiomatic. When you say "she knows her X" this tends to identify X as an area of specialization. For example

Fred knows Python.

(= Fred knows someone called Python => We might guess Python is a person in this case)

Fred knows his Python.

(= Fred is well versed in Python => We might guess Python is an area of expertise, e.g. the Python programming language in this case)