LOLZ. Sorry...
People steal other's ideas all the time and perhaps scientists and novelists must be capitalized first for proving, using, borrowing (and whatever they are justifying for anyone's sake) st that eventually leads to their Nobel prizes, media's attentions and ironically our praises. (We have to say the powers of 'Thank you' and 'I'm sorry' are incredible. Hell no, what does your teacher say about the originality of a story? It's not necessary to be 100% of your own fibres because, to cry out loud, who can prove they are 100% raw of their so-called 'own body' and whatever they're talking or using are of their own creativity? For instance, excuse me, their language is a proof of their plagiarism! No defense! Now they say they're paraphrasing with a divine purpose of contributing to human's value. They're right and you know why.
What you're mistaking to is public or human being's common knowledge. People have similar characteristics and emotions (even two fingerprints can be exactly the same!) so it's inevitably unavoidable to think of yourself as a plagiarist if you're kind of paranoid plus, fortunately, interested in extending your abilities. I used to wonder if my teacher would blame me for writing st similar to a famous story but by the end of the day, she didn't even notice which novel inspired me. It was because whether I was too good at disguising my writing or I actually got my own story. Thus, be smart to clarify which is original inspiration and which is blatant copying.