This is my first post and I'm fairly new to this site, so I apologize if this has been covered a lot.

They expect you to lie to the control questions, but what if you don't? What are they comparing the relative questions to?

Doesn't the physiology change during the lie (supposedly) due to guilt? What if you're asked a question that the answer is no, but something in the question creates a feeling of guilt? 

What if the answer is maybe? Example: have you talked with anyone under 18? I might have, like through a drive thru, but I don't know their age. Even if the intent of the question is talked meaning flirted or something inappropriate, that doesn't change the answer. Plus, I'd think a maybe would be closer to yes than no.