Quote by DanielleX
The correct English would be:
"I love people who know how to use their head."
"By definition, the term 'patriots' represents people who love their country."
"Generally speaking, most humans breathe through their nose."
And I'm not sure if it helps, but here's how I think it works: people, country, and humans are collective nouns (not sure if that's the word), so 1 person/ human being = 1 head/nose. People is used because "persons" is not right. And "most humans" would be pretty much the same as "people" and since we can't guess the gender of the people, or the humans on those sentences, that's why "their" is used.
It's the same with "country", the only difference is that that sentence makes reference to just 1 country, if it said "countries" then we would be talking about different groups of patriots, that love their respective countries.
But now, I'm confused with these:
Quote by DanielleX
"Women should be free to do whatever they want with their bodies."
"The men removed their hats."
I get your confusion, I would have said "The men removed their hat" and "Women should be free to do whatever they want with their body."
Because 1 woman = 1 body and 1 men = 1 hat. Using the plural form "bodies" and "hats" would imply, in my language, that 1 woman has more than 1 body, and 1 men is wearing more than 1 hat.
And I guess that
"The people were walking their dogs." or "The people were walking their dog." depends on perspective. The first one would mean that there are a 2+ dogs being walked by 2+ people. While the second sentence, means that, for example, it could be a couple walking just 1 dog.