James Hamblin, writing in The Atlantic (Answers to Every Possible Thanksgiving Health Question):

Is it actually healthy to celebrate Thanksgiving, though?

The holiday is predicated on the myth of an amicable arrangement between European colonialists and Native Americans. It promises a sort of absolution for non–Native Americans — from guilt in the taking of land, the genocide, and the slander and cultural erasure. This can’t be healthy. But recognizing the fallacy and refusing that absolution is probably a worthwhile exercise.