They want to use carbon dating on a person that is still alive... that's not how it works. Carbon dating measures how much the carbon 14 is left in you because

They want to use carbon dating on a person that is still alive... that's not how it works. Carbon dating measures how much the carbon 14 is left in you because it decays and goes away if not replaced by new carbon 14. Carbon 14 is created in the upper atmosphere and absorbed by plants. What it really measures is the period of time since the last plants you ate died.