Ha! I see that “swój” and its different forms are not going to win any popularity contests when it comes to Polish grammar for foreigners. And honestly, I can’t blame you guys. Those little buggers are really annoying.

I’ve seen some really convoluted explanations of ”swój” and so I’m not all that surprised by your comments regarding this particular possessive pronoun. On the other than, I am not sure if my explanations can be any better.

But let’s give it a shot and see what happens. And first things first:

• swój (masculine), swoja (feminine), swoje (neuter), swoi (plural masculine personal), swoje (plural, all others)

Now, take a look at these two examples:

• Dała to jej rodzicom. – She gave it to her parents.
• Dała to swoim rodzicom. – She gave it to her own parents.

Do you notice the difference? From the first example, we can deduce this thing:
that a female gave something to parents of another female.

Compare it with the second sentence. Here, it’s clear that a female gave something to her own parents.

At its most basic that is the difference between a “regular” possessive pronoun and this “swój” business. – It is used when a 3rd person possessive pronoun refers to the subject of the sentence. In our case – the parents of this mysterious woman who was the subject in our example.

It gets all goofy, however, when “swój” is used in the first and second person. Like this, for example:

• Mam swoje powody. – I have my (own) reasons.
• Przyniosłaś swoja książkę? –Did you bring your (own) book?

See what I mean? Why can’t we say “mam moje powody” and “przyniosłaś twoją książkę”? Technically, the grammar is correct, and technically it shouldn’t be wrong, yet, for a native speaker “swój” is the only proper choice in those sentences. And that is regardless of what Polish textbooks written by foreigners tell you.

I would say that in the beginning it’s probably best to remember that “swój” refers to one’s own something-something.
And the easiest way to remember it for a long time is through this:

• On kocha swoją żonę. – He loves his (own) wife.
• On kocha jego żonę. – He loves his wife. (which in this instance would be not his own but some other guy’s wife)

That should help you (or at least my male readers) remember when you should use “swój” and when it’s time for a different possessive pronoun.