Most school teachers will tell you that tongue rolling is an autosomal dominant trait. They are lying (or are, at least, misinformed). In fact, nobody really knows whether this is true. Other traits previously thought to be inherited from your parents, such as hand clasping, earwax type (yup, there are scientists that really research this!), whether or not your earlobes are attached to your head, and handedness have been questioned at some point. Are they really inherited?
Some research from 1952 by a guy called Matlock suggested that tongue rolling is not inherited. He showed that twins don't always share the ability to roll their tongues, which is a little odd as identical twins have the same genes. If it was an inherited trait then identical twins should be identical in their ability to roll their tongues. In fact, Sturtevant, the scientist who originally said tongue rolling has a genetic basis later changed his mind and retracted the original paper. However, no one seems to have caught on to this yet and lots of school textbooks will still list tongue rolling as an inherited trait.
The problem is that genetics is a bit hard to always interpret correctly and you have to remember to take the environment into account. If you only looked at traits shared between related people, you could accidentally determine that a lot of characteristics are inherited when they're not. Obesity, for example, isn't hereditary, but overweight parents do tend to overfeed their children, making them overweight as well. In fact, only 10% of body weight is influenced by genes, everything else is environmental.
So there you have it, eye colour and a number of horrid diseases can be inherited but no one can be decide about tongue rolling. Sorry to have to break this to you. If you don't believe me you can have a look at some of the papers that disproved it:
N. G. Martin (J. of Heredity 66:179-180, 1975) and Matlock ("Identical twins discordant in tongue-rolling." J. Hered., 43:24. 1952)
