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She's widely considered one of the most beautiful, glamorous women in the world, but Charlize Theron is totally down for diaper duty!

On Wednesday, Us Weekly broke news that the single, Oscar-winning star, 36, had adopted a baby boy named Jackson.

The Young Adult star was all smiles hours after that surprise announcement at Soho House in West Hollywood for the Hollywood Reporter's 25 Most Powerful Stylists Luncheon; flawless as ever in a sexy black minidress, Theron was mum on the baby news.

But a source close to Theron confirms to Us that Jackson is an African-American child, whom the star adopted stateside.

"This just came up again a few months ago [when] the baby became available," the insider tells Us.

Theron, who hasn't had a serious relationship since she and Stuart Townsend ended their nine-year partnership in early 2010, has "always always wanted to be a mom," the insider says, adding that she has no qualms about being a single mom. "She is glad to be able to do it on her own now -- and is so happy to be a mom!"