Former US diplomat Mike secured her an internship as a junior press officer in the American embassy in Argentina when she was considering a career in international relations.
However, he doubts he will ever hear from the 38-year-old former actress again.
Mike, who is the elder brother of Meghan's estranged father, Thomas Markle, told the publication: “Meghan has climbed socially and left us behind — that’s how I feel.
“I think that’s what happens when you’re ‘underclass’ and trying to rise above the reality of your situation."
Her uncle even detailed his thoughts on the famous royal rift, and Meghan's rivalry with her sister-in-law, Kate Middleton.
“Coming from her background, she may have a chip on her shoulder," he said.
“It could be that that’s part of the problem she’s having with her sister-in-law.
"Meghan is immature in some ways.
“I feel that because of the way she acts — not only towards family members, but other people.”
Mike revealed that he felt deeply hurt at not being invited to Meghan and Prince Harry’s wedding in May 2018, which her father Thomas also didn't attend.
He also blamed her father Thomas for her strong personality.
It could be that she’s bossy towards staff because she’s been spoilt by my brother,’ Mike said.
"He doted on her a lot — more than he did his other children.
"Tom spent more time with her and helped her in school and stuff like that.
"Tom has more of a rapport with her than with the rest of the kids. That’s a problem.
"She’s a prima donna because he treated her really well."