All she's saying is that since in the real world it DOESN'T work like that (with the black hair thing) but in Westeros it DOES then rather than have exhaustive arguments on message boards about how DNA works we can save ourselves the trouble and just say that DNA doesn't follow the rules of science which we know in reality in Westeros and it might as well be because of magic.
Kind of like the 10 year long summer thing. Or people who don't die when they walk into an inferno. Or zombies... hey I know let's get all snippy because in Westeros there are zombies but no bath salts! Source please! How could this be? I demand Martin provide some link to what we know as fact that these homeless wildlings from the north wouldn't behave like the shambling dead without crazy drugs like that guy in the news! How dare he ignore science in his fantasy story?!
I wish someone would ask Martin about this DNA thing so he could go all Shatner and be like, "Why are you breaking my balls do I like I have a biology PHD? I made it up! It works good enough, it's an awesome story is it not?" then Neil Gaiman could saddle up and let people have it again. When Neil Gaiman got all mad before I felt the same as a fantasy fan as I did as a hockey fan when the Great One got all mad at the Salt Lake Olympics. "Holy crap look at Wayne getting all mad! Things have clearly gone too far."
I'm sorry. I recently went from coffee twice a year to coffee several mornings a week and I'm sure this won't be the last morning tangent that results. In closing I'd like to demand that Martin expose the clearly evident use of growth hormones on those poor wolves before I get PETA on his ass.