I've heard that curling your tongue is genetic,

While I can curl my tongue, I was miffed as a child to discover that I do not have the (apparently) genetic ability to wiggle my earlobes. I also envied a friend who could wrap his thumb around the back of his little finger, and was the only person I have ever met who could twiddle both thumbs simultaneously in opposite directions (clockwise and anticlockwise). The hours I spent trying to do that!