mixing marans colors is no worse a crime than mixing ameraucana colors. Anyone who gets a hen of unknown origin and bases a pure bred show quality breeding project off of that hen is a fool. You want dark layers for your son, cross away. You have my blessing. There are well known and respected breeders who sold supposedly purebred eggs for $240/six eggs who knew their lines carried wheaten and no one shut them down or ran them out of town. Since you have wheaten, you can always test breed future hens if you wanted to go back to non-wheaten carrying lines. Wheaten is WAY simpler to get rid of than many of the other problems that plague marans today. Crossing the lines could introduce hybrid vigor, and conversely it is rumored that it could lighten your egg colors. I have not seen that to be the case, however it is rumored to be true. I think you got the gist of the genetics lesson here. The moralizing and catastrophizing, you are on your own with that! Good luck in your efforts and DO please keep us posted and post pics!