I’ve got my fair share of unconscious habits: running my hands through my hair, tapping my feet, pursing my lips when I’m concentrating—and, of course, cracking my knuckles. That last one is perhaps ...

I’ve got my fair share of unconscious habits: running my hands through my hair, tapping my feet, pursing my lips when I’m concentrating—and, of course, cracking my knuckles. That last one is perhaps ...

If you're a kid, chances are you either crack your knuckles or know someone who cracks theirs. You might have been told (by annoyed parents, perhaps?) that you'll develop arthritis if you keep up such ...