I learned both as soon as I got my learner's permit. We had a '48 Chevy truck with manual (and a foot-pedal starter!) and a '68(?) Rambler wagon with push-button automatic. (Man, that was fun to drive!)

Because I've mostly had manuals, I plant my left foot firmly on the firewall when I'm driving an automatic. "Clutching" the brake pedal is Double-Plus Not Good.