"OK, I'm sorry but you are just not Bert. I remember you from elementary school, but you are not him. You just don't look like him.

How can I believe you when you can't offer me any genetic proof that you were him. You say you don't even have an original sample to show me.

Look, you don't look like him, you don't sound like him. The only thing the same about you and him is that you both sound like pretty smart people. However, that could be further reason for me to be wary of you.

Look, we have all genetically altered ourselves in some way. Even I have made some cosmetic modifications. But I have a detailed and authenticated record of my DNA history - I can prove, legally, that I am who I say I am.

You, 'Bert', cannot prove it legally or scientifically.

I feel torn because you may very well be my childhood friend Bert. But, alas, the proof is nowhere and thus I must err on the side of logic.

After all, friend, Logic exists, even where reason can find no hold."