F2 eggs from the Silver Wheaten, back in 2010. They have pretty much maintained this color since. I need to put updated egg photos up from what's laid this spring (2015), just not all are laying yet.
Feather color has nothing to do with egg color genes. It's all in how you breed them and never back breed to the non-Marans (in this case Sussex) line. Ever. When transferring a feather color gene. A one time breeding is all you need.