My daughter asked me the question, the one that every parent feels that they have to answer, but how far into detail do you go. I didn't want to go with the birds and the bees (how uncool is that mess) but the alternatives seemed worse. Then I thought about the traveler and its light and the guardians. I told her of the travelers light and how it goes into the guardians and they gain superpowers (she watches me play all the time so she got it) The rest got even more awkward but in the end I told her that her superpower was having babies. Thanks Bungie!!