Board Thread:Warhammer 40k General Discussion/@comment-6078851-20150114163201/@comment-8881468-20150127180338

Yakonani wrote: I thought the same about genome adapting to the conditions of the worlds they live, depending on were they came from astartes would be all different skin colors, so the Black Templars and Dark Angels whom come from all different places should be very diverse, but an Chapter that is recruiting from a Feral World, it would depend on the world.

So in my opinion, astartes would be all different skin colors and stuff. as the gene-seed of their respective primarchs and the melanchromatic organ especially, override their original gene-code, they will look more like their primarch than anyhting else.