Is there any way to mark a Descendant of Heroes, currently there is no way to know unless you bred it or it qualifies for a quest or Island building with that criteria, it would be nice if something like a red dot or number was put somewhere so you know what you have, I usually mark it in the comments & am thinking of making a list since I just noticed that I put 1 of my Descendant of Heroes unis in the pound not remembering that that's what it was.

Descendant of Heroes is the same as Genetic Power. A Descendant of Heroes in 1 Generation is a GP1, Descendant in 2 Generations a GP2 and so on. As such it is possible to see which ones are Descendants by checking their Profile page and checking their Genetic Power level.

However, I think it should be put in the FAQ that this is indeed the same thing.