The word "parents" is a plural noun. A person normally has two. The mother is one parent, and the father is one parent. Are these oranges or grapefruit? These are your parents, aren't they? What are those? What are these? (when pointing at several objects)

I agree with Chris and Randy, so I will not comment on their answers. I will say that watching movies or TV shows and assuming that the grammar used is correct is a mistake. While watching English language media, or listening to English language music can help you improve your English in many ways, you should not always assume that grammar will be one of the things helped. In friendly conversation, for a variety of reasons, people use improper grammar, and this is exaggerated in entertainment events. So, please continue watching and listening, but also remember that mistakes are common and if you think someone's grammar on TV or in a movie is incorrect, just ask us about it, and you will probably be right!

If there a r e a few oranges or grapefuits in front of you,you can say "Are these oranges？” Similarly，if there i s only one orange in front of you,you can just ask :" Is this an orange?" Bur for example:There is a friend of yours,who says," I'll have a surprise for you! ",and he put a lot of books which you like in your room before you find out.When you see those books in your room,you telephone him,say:"This is what you wanted to show me?" in a spoken way.You don't need to say:"these are what you wanted to show me?" like a robot:) though they are books not one book. Do not try too hard to get the rule,just watch the sentences as much as possible,and you will master them just by feelings.

"These are my parents" is the correct alternative.

Imagine I´m showing you a picture of my family. should I say: Tese are my parents. Because if it´s a photo of some friends of mine, I´d say "this is John and Mary" instead of "these are John and Mary? What do you think about it?