What is the hottest age?

What do Natalie Portman, Rachel Bilson, and Sienna Miller have in common?  They're all at their most beautiful age. Well, at least that's what study of 2,000 British men and women found.
The subjects said that women in their late 20s and early 30s were more attractive than those at other ages. And the peak of hotness was deemed to be age 31.
Now, we're not scientific or anything, but we took a look back at the style evolutions of the actresses mentioned above, and - whether it's just that their old looks are dated or that with age comes confidence - we tend to agree.
What do you think?  Is 31 the hottest age?  Or do women peak younger or older?

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