This is opinion.  It is to be taken as opinion.  Anyone who takes it any other way can note the mistletoe attached to my shirt tail ... ummm ... when I remember to wear a shirt that actually has a tail.

I have two projects in the works that requires models of people in my life from as long as 60 years ago.  I don't have photos or anything but I do have memories that are still reasonably sharp - sharp enough to work from.  (I had photos and they arrived at LAX with me but that bit of baggage never made it to HNL.)  When the models "come to life" for me, I'll consider them complete. Will they be absolutely picture perfect?  No, and I don't expect them to be.  Will they be as close as I can make them?  Yes.  That, to me, is realistic. 

With that, I believe that anyone who insists that his/her work is realistic and that of others isn't because (s)he works from real people as his/her sources is only fooling him/herself.  A 3D model is not a photograph in 3 dimensions.  It is, at best, a simulation of a real person as seen through that individual's eyes.  We have seen in this thread photos of two people who would be considered "unrealistic" if exactly modeled, the ever delightfully lovely AO and that guy who so resembles the Tazmanian Devil cartoon.  (We all remember Taz, rght?)  However, since they don't fit the model of "realistic", they don't exist.  (Sorry, dear AO, but you're obviously only a figment of some artist's over-active imagination.) Come to think of it Twiggy & Tiny Tim and the really tall Chinese basketball player whose name I forget don't exist either.  They aren't "realistic."

Look at Reby Sky who, incidentally, I do not find attractive at all.  There exists a model (actually two built on different core characters) that has been touted by some as "realistic" simply because it is based on a real person.  Looking at renders using that model and at photos of the lady herself, I find nothing but a superficial resemblance.  This is true of other models based on real people as well.  Close but not cigar-worthy.

The universe does not adhere to man's "rules" and, contrary to the belief of some, never has.  That includes the supposed rules of heredity, genetics and about anything else that can be made into rules.  Over the past 68 years I've seen people of all sorts, sizes, colors, shapes etc who don't fit that "realistic" mold - don't fit the "rules."  Out of the ordinary, yes, but they all were very, very real.  This tells me that those "rules" are general suggestions rather than hard and fast law and are notable more by the exceptions.  Some things are obvious.  For example, I've yet to see a human being with purple skin.  Or yellow eyes.  Or naturally green hair.  Well, not when sober, at least ... and I went clean & dry in 1968.  OTOH, I have seen people with unusually long canines who could be mistaken for vampires.

What does this have to do with Dawn?  Very simply this.  Saying she's not realistic because she's not based on a real person is rather myoptic.  If one looks around long enough, one can find a "prototype" for her and a great number of other supposedly not realistic models.  But basing only on photographs is taking a very, very, very narrow cross section thinned by blind obedience to manmade rules that nature doesn't acknowledge as law.