it's sharper than their picture of bigfoot. 
I have no idea if it's true or not, although they have been very coy about this one; letting the story out in dribs and drabs to prolong it. but you have to admit, it already walked like a duck, and now it's beginning to quack.
A trial attorney like the Breck Girl know instinctively what he should be doing to nip this in the bud, were this nothing more than a scandal rag trying to make hay on a story with nothing behind it.
Sue the shit out of them.
Call a press conference, and in front of all those adoring media shills, swab his cheek and hand it over for DNA comparison testing. Assuming the Breck Girl is innocent, he can then loudly proclaim thus, and promise them that the proof of his innocence will be back in 48 hours to a week - however long it takes for a reputable independent lab to run the DNA test.
He then gets to take the National Enquirer to the cleaners for libel (It's been done to them twice before in the last 10 years, so he's got plenty of case history to use against 'em) with the media and the entire liberal mob behind him.
The fact that he isn't doing this says to me that his case against the Enquirer isn't quite so airtight as he might like it to be.