I can; my spouse can't. Only two of our three children can. We always thought it was genetic--you either could or you couldn't, depending on your DNA. Turns out, it's not that simple.
Mu Shu, here, clearly can curl his tongue. And he enjoys asking the question of his friends at the dog park.
Sometimes they're not sure.Sometimes they're looking at the wrong end to find out.
This guy above, in the light-green halter, was eager to show off his ear-flipping skills.
But on the topic of tongue-curling, he stayed mute. Spoilsport!