How do you "know".
Did they purchase it from nerd?
Here's an interesting point Subdriven brings up...
Why do both parents need to be from NERD?Subdriven
Anyone can call there pastel a lemon pastel but only if you KNOW the parents are BOTH from NERD
Wouldn't a normal X NERD Lemon pastel make more lemon pastels since that gene comes from the pastel and not the normal?