A gerund is neither a verb nor a noun, but a little bit of both. A gerund resembles verbs in that it can take
a subject and
an object:
I insist on him/his buying a car.
Nouns don't take subjects or objects. You cannot say: I girl her, or: We discussion him. Only verbs can take objects. Since a gerund has substantival qualities as well, its subject can be in the possessive case (my, our, John's etc.) It has long been customary to prefer the possessive form especially in written English when the subject is
a personal pronoun:
Can I count on your doing it?
Do you enjoy his talking about his achievements?
In spoken English
the object form of the personal pronoun is more common, and the roots of this usage are buried deep in the history of the language:
Can I count on you doing it?
Do you enjoy him talking about his achievements?
When the subject of a gerund is
not a personal pronoun, there is a long tradition to use the common case, which corresponds to the object form of personal pronouns as there are no inflected forms in English for nouns acting as objects:
Can I count on John doing it? Can I count on Mr Smith doing it? Can I count on your friends doing it?Do you enjoy John talking about his achievements?Since many people think that it is somehow 'better' English to always use the possessive form, the editors of
Newsweek International, for instance, have begun to prefer the possessive form even with nouns. There were no signs of this about 30 years ago, but these days one often sees sentences like this:
Do you enjoy John's talking about his achievements?I suggest you say and write what you think sounds and looks best. You can't please everybody anyway. I must say I would steer clear of sentences like this:
He insisted on my and my brother's coming along.
We relied on everybody's learning it.
For those who insist on the possessive form, there is no other option.
Cheers
CB