A friend who is learning English asked me this question today and I was unable to give a definitive answer on grammar.
The phrase constructions below are quoted verbatim from them :
- An English person generally has a pet
- English people generally have a pet
- English people generally have pets
Posibilities of tidying up the phrase construction aside, specifically in terms of the grammar:
My thinking is:
- (1) is incorrect, although I am toying with the idea that perhaps (at a push !) with a more specific subject it could be acceptable (e.g. a blind person generally has a guide dog)
- (2) and (3) are largely interchangeable, but if you were being strict about grammar, (3) would be the correct answer because of the plural subject.
However I would be interested to know what the specific grammar rules are in relation to generic constructs (both for my own interest and that of my friend).