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"It's sort of a genetic thing," Aniston tells PEOPLE exclusively of Theroux, who bared his nude frame on an episode of his HBO hit, The Leftovers. "He can work out or not and he has that body. It's not fair!"
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Aniston, 46, does give credit to her 44-year-old husband, whom she wed last August, for his "very healthy eating" (he also shuns sugar), but insists that Theroux is also just inherently blessed.
"It's sort of God-given," says the smartwater sparkling spokesperson with a laugh. "And an 'F You' to all of us!"