Can you then pass the feature on to your children or is it strictly limited to you ?
They didn't clearly explain. But if an elf and a human have a baby he can LOOK like a human or an elf, and have the abilities of a human or an elf. It's clear, that if he looks like a human and have the characterics of a human, he's a human, same with a matching elf. But if he looks like one and have the ability package of his other parent, he's a half-elf, half-human. It make sense that a character saying "My mommy is a half-elf, my daddy is an orc" can have, applying the same rules, the choice of getting orc look, half-elven look and orc abilities or half-elven abilities. It fits Occam's razor. It requires no new rules. The alternative requires determining which racial traits are dominant, because if it isn't passed to children, your half-elf (human look, elf power) mating with an orc, would, say, bring human power to the child... despite the parent having no human power. It's not unheard of, but it would require determining for each pair of races which one are transmitted to children. A lot more rules, for very little benefit. So, I'd say that unless we get more details on this than a side bar, it's reasonable to assume that each parents transmits his own powers and appearance as a choice to child.