I’m not a native speaker, and when I’m writing in English, I often wonder which form of genitive I should use. There are two possible genitive formations in English, the one wit the apostrophe and the one with ‘of’ (I’m sorry that I don’t know the technical terms). Which should be preferred on a, let’s say, educated level, like it is mostly used on the SDMB?
This is going to depend on what type of genitive and the context of the phrase.
For non-possessive genitive, I think -s forms are preferred:
At arm’s length; six weeks’ pay; an hour’s time (apostrophe increasingly optional, especially in the plural)
For complex, multi-genitive phrases, I think one “of” is preferred to front the ultimate subject:
The aunt of my sister’s cousin’s boyfriend
For genitives of quantity (I don’t know the technical term), perhaps the of:
A keg of beer; a loaf of bread
Same with partitives
A mug of beer; a slice of bread
So far as I know, either is acceptable in any context. The apostrophe s version is quicker, but sometimes the “of” form can reduce ambiguity or awkwardness. So, for instance, I’d probably refer to “Bob’s mother”, but “the mother of Bob’s cousin’s roommate”, since three apostrophe-s words in a row would be awkward.
Then there are some phrases that have a customary form-- For instance, Mary is sometimes referred to as “Mother of God”, but not so often “God’s mother”. But tradition on that particular phrase is the only reason she’s not: The latter would be grammatically acceptable.
EDIT: Dr. Drake makes a good point with his last examples: You’d never say “beer’s keg”, or “bread’s slice”.
What is your native language?
It is NOT the case that one usage is more “educated” or “formal” than the other – they are used in different constructions, but there is some overlap. Experience with the language will help you feel which one to use.
I would say that the possessive with apostrophe and “s” (as well as possessive pronouns: my, your, his, her) is used for cases of ownership and belonging: the man’s dog, the wife’s hat, the horse’s hooves, etc. The other usage with “of” is used for the other genitive uses (although they are not commonly called genitives in English, except by analogy with other languages.
In NONE of the following cases would we use the apostrophe-“s” construction. (The labels I use for the following cases come from my study of Greek grammar, however.)
Partitive Genitive:
“all of them” “part of the group” “half of the team” “the back of the store”
Genitive of Material:
“a bucket of steel” “a rod of iron”
Genitive of Content:
“a bucket of water” “a glass of milk”
Genitive of Apposition:
“the land of Egypt” “the city of New York”
These are just a few examples.
In some other cases, they are fairly interchangeable, and subject to stylistic and literary variation: “The tires of my car are flat.” “My car’s tires are flat.”
I hope this helps a little. Let us know some specific examples, and we will tell you which of the options is preferred.
First, thank you all.
German. We have some similar cases of genitive formation, and since I use them intuitively, I rarely thought about their uses. But after reading the posts, I understand that they are similar in both languages.
I thought of simple examples like:
The actor’s name (x)/The name of the actor.
The ball of the child/The child’s ball(x).
I marked the ones which I would prefer. But in the first case, I’m rather undecided. Perhaps it depends on the use of the phrases in the context of a certain sentence.
(…in the context of a certain sentence…) There you have your third example 
Studies have been done on this. For example, this book goes into it in nauseating details. From the quick summary on page 165, the upshot seems to be that things are evolving, and that young people and Americans are somewhat more likely to use the 's form.
This abstract (PDF file) may also be of interest.
In cases like this, they’re usually both right but the ‘of’ is putting unusual stress on the item in question, and can sound a little hinky if that’s not what you’re meaning to do.
Most of the time, the apostrophe ‘s’ is fine. The “of” can often sounded stilted in English.
If you mean to convey possession, most of the time you’ll want to use the apostrophe form:
the child’s ball
the actor’s name
the car’s steering wheel
the painter’s technique
Using the “of” form in these situations isn’t incorrect – people will still understand you – but it often sounds a little stiff and forced.
However, you should generally use the “of” form if you link two genitives together. For example:
“The steering wheel of Brian’s car” instead of “Brian’s car’s steering wheel”.
And occasionally you might use the “of” form if you want to put particular emphasis on the possessed object. For example:
“The actor’s name is Chuck Norris.”
vs.
“The name of the actor is Chuck Norris.”
You’d use the second form if you really wanted to make an unambiguous point. The message is “I’m not just mentioning this casually. I’m telling you an important fact about a NAME, so pay attention.”
American-English speaker here. In general usage, both ways to phrase that first construction are pretty close to even in terms of preference. “The name of the actor” doesn’t sound stilted to me at all, and just as natural as “the actor’s name.” However, with the second pair, “The ball of the child” sounds very stilted to me, and I can’t think of a situation where that would be the more preferred usage over “the child’s ball.”
I have no idea why this is so.
In your first example, both are acceptible. There will be some variation, depending on what your emphasis is. I would take “the actor’s name” to be slightly more a statement about an actor, and “the name of the actor” to be slightly more a statement about a name. The difference is slight, and both statements obviously involve both. They seem quite interchangeable.
I suspect that in the case of “The ball of the child/The child’s ball,” native English speakers would ALL find the first strongly objectionable. The only exception would be a case in which “child” is followed by several modifiers: “The ball of the child in black pants and a red shirt is round.” is to be preferred to “The child-in-black-pants-and-a-red-shirt’s ball is round.”
Yes, the 's can be separated from the noun! A famous example is Tyndale’s famous last words, “Lord, open the King of England’s eyes!”
It’s a funny accident that the two examples there can both be said with no genitive construction at all - of course “New York City” is the correct full name of the place, and “Egypt Land” is a construction heard in gospel music and similar contexts.
Yes, I noticed that myself. 
Surprisingly, though, it is common (though probably not proper) to say “a beer keg” or “a bread slice.” It seems as though in those situations, the first word becomes almost an adjective modifying the second word… I wonder where this came from?
Perfectly proper, in general. This is how attributive noun phrases – that is, consisting of one noun modifying another, and thus acting as if it were an adjective – come about. English speakers use these ALL THE TIME, but they don’t usually get the emphasis they should when teaching English as as second language.
You have a certain amount of freedom to express yourself with the “possessive noun genitive” or the “prepositional phrase genitive”, but there seems to be a standard usage that:
-
In the absence of a long phrasal construction, the possessive-noun form is usually used with people, including common nouns meaning people, and generally with animals bearing names and sometimes those merely referred to by their species. “Obama’s candidacy, George Bush’s Texas ranch, Queen Elizabeth’s royal prerogative, Joe’s watch, Rover’s bone, the cat’s toy, the hedgehog’s habit of estivating…”
-
Objects usually, and common-noun places nearly always, take the “of” form, but not always. This is something that it more or less takes a native’s ear to distinguish standard usage, and no one will think less of you for a contra-usage construction. "The footrest of the reclining chair"sounds more natural than “the reclining chair’s footrest” but both would be acceptable. “The terrain of south central Colorado” is preferable over “South central Colorado’s terrain” in most cases. I’d use “Chicago’s traffic problem” but “the traffic problems of Columbus, Ohio” without even thinking twice about which to prefer.
-
Long phrases nearly always take the “of” form for ease of construction. There’s a famous counterexample which most native speakers would find jarring: “Cromwell’s Roundheads lopped off the King of England’s head.” One would say “the office of the Deputy Assistant Secretary for Commercial Transit” in preference to somehow hanging a “-'s” somewhere in that phrase.
Let me mention in passing the “double partitive”. which often throws off non-native speakers.
“A painting of Churchill” would refer to a portrait for which Sir Winston sat. “A painting of Churchill’s” is a double partitive, and would mean, approximately, “one painting from among the ouevre of Churchill’s work as a painter”.
And that distinction would be 100% clear to a native speaker simply from the presence or absence of the -'s on the noun which is the object of the “of”.
My sense is that “beer keg” is normal as it were, but bread slice sounds odd. Perhaps beer keg seems natural because we talk of beer mugs. Oddly, we might speak of empty beer bottles that need to go back to the recycler, but we usually say “bottle of beer” when referring to the quantity of beer therein.
In any event “beer keg” and “bread slice” are actually compound nouns, just as they are in German (Bierfaß and Brotscheibe IIRC). English doesn’t form compound nouns to the same extent as German or Dutch, and the component words aren’t run together in writing, but it’s essentially the same principle. Writing and spelling usually don’t matter to linguists, except for purposes of illustration.