She may have been all natural at one time ...
but as this boob expert says, "Now, I'm no expert on Macromastia and Gigantomastia, but typically when a woman has one breast larger than the other and she later increases in size (either through natural growth or weight gain) the difference between the two breasts usually increases, but as pointed out by 'anon' they're now equal (almost anyway).
I'm guessing Ms. Crow had a fair sized pair to start with (GG cups) and didn't like the difference, and so
had implants in each to increase their size and balance them out.
Admittedly it's just speculation at this point, but combined with the picture of the makeup covered implant scars and I'm thinking they're definitely enhanced."
http://www.boobpedia.com/boobs/Talk:Leanne_Crow#Natural_.3F
I'll tend to go with that answer. Natural now enhanced.