Is Caffeine Addiction Genetic?

A conversation with my 7-year-old brother (who called me to see if I would do his math homework for him, which I did do the day I was being a hypocrite but held out today):

Me: You should go to bed. It's late.
Brother: I can't fall asleep.
Me: You should lay off the coffee so you can fall asleep at night.
Brother: Sometimes I don't drink coffee in the morning, but then I fall asleep in class.

I trained him well.

Also, this is like coffee porn (and I'm sure that phrase will do wonders to the search terms by which people find my blog):