I was watching this comic where the main character goes to the past due some incident, and then he goes on a time where he was a kid, he knows that he's trapped as a labrat, so tries to "rescue himself" saying "his brother is there" (he being his own brother).
So... I got curious about what might happen if someone made some DNA test to them, I mean, they are technically the same person, but with different age, I'm not sure how DNA tests work and what they might be able to figure out, or would the test response be taken as "being siblings"?