06/02/2011 02:13 pm ET | Updated Aug 02, 2011

Sienna Miller On Working With Sister Savannah: 'People Always Want To Hear About Some Sort Of Catfight'

It's pretty easy to forget that Sienna Miller is actually a working actress and fashion designer when her trysts with Jude Law or enviable outfits dominate the headlines.

But in a Herald Sun story from a few weeks back profiling Miller and her sister Savannah, the bubbly blonde refocused the attention on her seemingly-stable family life and impending birthday milestone.

The duo behind UK-based clothing line Twenty8Twelve, Sienna and Savannah are clearly two blonde peas in a pod. Writer Dan Rockwood describes the pair playing dress-up, giggling, and participating in the ultimate indication of BFF status: the completion of each other's sentences.

Sienna told the Sun, "People always want to hear about some sort of catfight, but we couldn't be closer....We understand each other on a real level. If we're both in moods, we know there's no need for communication; we read each other's vibes."

The younger of the two, Sienna will turn 30 before the end of the year, something that's inspiring her to get serious.

"Recently, I found myself thinking, I'm getting wrinkles. And things are wobbling, I should go to the gym," she admits. "Then I was like, f*ck it. That's not where the focus should be. LA is a nightmare for that. I say, people should be young and then be old."

So is she looking forward to leaving her 20s behind? "I can't wait to be seen as a woman," she says. "But I know I probably have to contribute to that with behavior."

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