grammatical number - "Everyone has their own stories" vs "Everyone has their own story" - which one is correct?

Which of them is correct?

Everyone has their own stories

or

Everyone has their own story

What I'm asking about is that how could we decide that we should use a plural or singular noun after the word "own"? Is it correct to think that if a subject of the sentence is singular then a noun following the word "own" must be singular too?

Here are some examples below:

People have their own stories.

Dang has his own story.

Evenyone has their own story.