Not to rain on your Thanksgiving Day parade, but the story of the first Thanksgiving, as most Americans have been taught it — the Pilgrims and Native Americans gathering together, the famous feast, the turkey — is not exactly accurate.

Thanksgiving facts and Thanksgiving myths have blended together for years like so much gravy and mashed potatoes, and separating them is just as complicated.

Blame school textbooks with details often so abridged, softened or out of context that they are ultimately made false; children’s books that simplify the story to its most pleasant version; or animated television specials like “The Mouse on the Mayflower,” which first aired in 1968, that not only misinformed a generation, but also enforced a slew of cringeworthy stereotypes.

High school textbooks are particularly bad about stating absolutes because these materials “teach history” by giving students facts to memorize even when the details may be unclear, said James W. Loewen, a sociologist and the author of “Lies My Teacher Told Me: Everything Your American History Textbook Got Wrong.”