I have to disagree in this case fveldig (although your numerous comments are most helpful, which I greatly appreciate). Due to the possessive "mine," it would never refer to another person's daughters, but I understand your meaning. It is not with the meaning of "As compared to other daughters, MY daughters are perfect" since this could be true if no other daughters existed in the universe, yet still MY daughters are perfect. Rather it has an element of pride that is highlighting that something(s) of Mine is/are perfect.
To Dino-Panda: The placement of the possessive places an emphasis on different aspects of the sentence: "Døtrene mine er perfekte" this typical and more-often encountered arrangement places emphasis on the idea that these individuals are Perfect. "Mine døtre er perfekte" is less often encountered, and thus places emphasis on the idea that specifically MY daughters are perfect (proud parent).
Both are correct arrangements, yes, but the choice in arrangement is not random or arbitrary, or a even matter of preference (as in I prefer in all cases to do it this way since I learned that way first), but rather a matter of what point/aspect one is trying to emphasize.
He is, yes.
j2neuby misinterpreted fveldig's statement, and then went on to say the same thing as fveldig meant in the first place: that the placement stresses the possessive. And why else would we stress the possessive other than to assert that it is indeed X's daughters who are perfect - as opposed to someone else's.
"Hennes døtre lager bare trøbbel, mens mine døtre er perfekte."
"Her daughters only cause trouble, while my daughters are perfect.
Hopefully, the concept should now be abundantly clear with the double (triple?) explanation. :)
I'll add that one needn't read too much into the placement. In speech, verbal stress will take precedent over word order, and even in writing one may place the possessive first at times just because it sounds better, or for a bit of variation in an otherwise repetitive text.