"de par"?

I'm reading a French speech on Monday, and I'm curious/confused about one of the edits my French teacher made. The original phrase was:

Les êtres humains sont, par leur nature, fortement irrationnelles.

Which was changed to

Les êtres humains sont, de par leur nature, fortement irrationnelles.

Neither I, nor my other french-speaking buddies can understand the edit. (We're all L2, but we've been in French immersion for ~13 years.) The purpose/correctness of the edit isn't really clear to us, but we're reluctant to challenge the judgement of our teacher, a native speaker (Franco-Ontarien, if that makes a difference).

So, is "de par" widely used? Is it more correct (in this instance) than just "par"? Why has no one ever taught us this before?

Thanks for any help.