He gets it from Dad.

Conversation of 12/7/2016

Dad: One of you please get the forks and one of you get the napkins.

Me: Oh, there aren't any napkins. There are a bunch in the dryer, but I haven't brought them up yet.

Finn: Thanks, Mum.

Dad and I look at each other.

Me in my sweetest Mumma voice: Thanks for what, dearest?

Finn: For washing the napkins and leaving them downstairs.

Dad and I look at each other again. I roll my eyes.

Mike in a whisper: I don't think we taught him sarcasm, I think he just has it innately.