This week's news that British actor Henry Cavill would play the title role in Zack Snyder's Superman: Man of Steel is part of a larger trend. From Canadian Ryan Reynolds (the Green Lantern) to Welshman Christian Bale (Batman), from Brit Andrew Garfield (as Spider-Man) to Australian Hugh Jackman (Wolverine), it seems that only foreign actors are being cast as American superheroes. The phenomenon has incensed some, including a commentator at fanboy site Ain't It Cool News who writes of Cavill's selection, "This casting is fundamentally anti-American. It's disgusting casting... I will never ever see a movie with a Brit as Superman." What's behind Hollywood's controversial superhero outsourcing? Seven theories:

1. American actors aren't manly enough
Most American leading men in their 20s and 30s are "very boy-like," says John Papsidera, the casting director on The Dark Knight and The Dark Knight Rises, as quoted in New York. Too many of them, he says, are more in the tradition of a Dustin Hoffman than a Steve McQueen. "Take Jesse Eisenberg: I put him in Zombieland, but he's not going to play Superman... [and] Inception was the first time Leo [DiCaprio] seemed to have fully grown into a man." 

2. Or they're too closely associated with other roles
Many of America's young men are already well known for their parts on popular television series, and the studios don't want to impose the "baggage of another role" on a highly valuable superhero brand, says Louise Ward, an agent at United Talent who represents Channing Tatum, as quoted in New York. "Kids are not so easily fooled anymore. They'll say, 'Oh, it's that guy from 'Gossip Girl!'' or 'It's the girl from 'The O.C.!''"

3. As a whole, the American male has been feminized
It's not just that America's actors aren't macho, it's that the country's larger culture has softened its men, agent Louise Ward goes on to say. "There's been a certain feminization of the American male... there are a lot of 'mama's boys.' Kids are raised like veal. We're afraid to let them play soccer. That kind of nurturing softens what we're used to seeing on the screen. American men aren't men on the screen." By contract, she says, men raised in Australia or the United Kingdom, are "still raised as men," giving them an "easy masculinity" that plays well on screen.

4. And the manliest guys are steered away from acting
Even if an American boy displays a talent for acting, "he's steered towards athletics in high school," says an anonymous agent, as quoted in New York. "Kids who want to do theater, or study acting, well, they're immediately labeled 'wimps' or worse, 'fags.'"

5. Foreigners are just more talented
"I hate to say it: They’re better actors," says an anonymous talent agent, who had a client in the running for the Superman role, as quoted in The Hollywood Reporter. This is part of a bigger phenomenon, says Borys Kit in The Hollywood Reporter. A "similar invasion" is occuring in television, with foreign leading men in key roles across all genres, from the medical drama "Off the Map" to zombie comic book adaptation "The Walking Dead."

6. But the cross-cultural casting works both ways
While it's "weird" that all these foreigners are being cast as American super-heroes, "pop-cultural cross-pollination has a long, long legacy," says Scott Thill in Wired. Robert Downey Jr. is shooting his second movie in the role of the vaunted British detective Sherlock Holmes, and Shakespeare has been performed in different languages and styles for centuries.

7. And it all could just be a coincidence
It's possible that given "today's access to a larger pool... this is all nothing more than a coincidence," says Robert Falconer at CinemaSpy. "And at the end of the day, the performance is really the only thing that matters."