I'll weight in on this discussion.

In my opinion, most buyers (that I deal with) want to know details like this. They want to know the linage, birth date and parents.

To cut down on questions, I have begun to try and put everything that I think an interested buyer would want to know about the animal on sale (so I was and am considering putting in the clutch information)

From my breeding experience..morph siblings do tend to be more "eye-catching" than normal Normals. I do believe that the morph gene does have some impact on their coloration and patterning and while some may not think they are worth any more than a normal Normal, there are some that are willing to pay a bit extra for a very pretty pet or a very pretty patterned female morph sibling.

We already know that the patterns do carry weight on further breeding attempts, and that very unusual colors and patterns in Normals does make them more "special" than the regular Normal (Normals are not created equal).

So as long as the ad is honest, breeders/sellers are free to put whatever they want in their ads.