Thank for the read Angel!!!  As for Ethan, he was raised around humans.  Keith never denied him time away from his human siblings even when he was evolving into an adult.  Maybe I'll tell his full tale one of these days in an off shoot story.  Ethan is an interesting titan who understands human nature because of not being denied.  Elisabeth and Tomas are a different story.  Jane raised them pretty much on her own with only limited time with Sven.  You'll find out that Elisabeth and Tomas only know of humns by stories the giants and the titans would tell.  Jane isolated the twins whenever Ethan had his special visitors. 

There bodies become adapt to handle their massive size.  The titans and the giants are majority muscle and bone.  The titans have learned to eat less than the giants too by their personal science.