How Can You Be from the Past and Not Know Anything About It?

An Excerpt from The Tomorrow Paradox (Book Two in The Adventures of Mackenzie Mortimer):

Mackenzie sighed. “At least you’re safe, but we have to figure out a way to return the real Brandy and get you back to Mortimer Enterprises.”
Gemma pinched his cheek. “I miss you too, sweet cheeks. But I’ll be safe for now with Granny Carmichael. You’re the one in danger.”
“What do you mean?”
She pointed to Drake. “That hottie with half my DNA says he’s tracking a time traveler so his father can make an...