Michael Oher, a foster child in Tennessee, is adopted by a wealthy white couple and blooms into a star college athlete.
In a court filing, Mr Oher, now 37, alleges he was never adopted and was instead tricked into a conservatorship.
Leigh Anne Tuohy made millions of dollars from his name.
Representatives for the Tuohy family and foundation did not respond to the BBC's request for comment.
But Sean Tuohy told the Daily Memphian website that he was shocked by Mr Michael Oher 's allegations.
Michael Oher ’s petition claims that as conservators, the Tuohys were able to sign deals that earned them and their two birth children millions of dollars but excluded Oher from any of the income. Oher says the family earned millions in royalties from The Blind Side, which took more than $300m at the box office; but he got nothing for a story “that would not have existed without him”.
Michael Oher,” the petition alleges. “Michael Oher discovered this lie to his chagrin and embarrassment in February of 2023, when he learned that the conservatorship to which he consented on the basis that doing so would make him a member of the Tuohy family, in fact provided him no familial relationship with the Tuohys.”
The legal papers say he found out in February "the conservatorship to which he consented on the basis that doing so would make him a member of the Tuohy family, in fact provided him no familial relationship".
"At no point did the Tuohys inform Michael that they would have ultimate control of all his contracts, and as a result Michael did not understand that if the conservatorship was granted, he was signing away his right to contract for himself," the petition claims.
For years, Oher has said, he was content to live with the myth created by the movie, reasoning that its inspirational message outweighed the pain inflicted by what he saw as its inaccurate portrayal of his life. But that has changed.
"There has been so much created from The Blind Side that I am grateful for, which is why you might find it as a shock that the experience surrounding the story has also been a large source of some of my deepest hurt and pain over the past 14 years," Oher wrote in his book "When Your Back's Against the Wall," released last week.
"Beyond the details of the deal, the politics, and the money behind the book and movie, it was the principle of the choices some people made that cut me the deepest."
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