I'm pretty sure I was born sarcastic.
Third birthday. I didn't want to have my hair brushed. I ran from my mom and refused to let her anywhere near me.
My mother, exasperated: "Sit down, you look like a heathen!"
Me, eyeballing her pajamas: "Well, you don't exactly look like a bowl of fruit yourself."
What's the first time you remember being snarky?