Are motor tics hereditary?

Yes and no. Motor movement disorders are usually inherited, but may also be acquired. Acquired tics are part of panda's, a neuroautoimmune disorder that causes inflammation in the brain's thalamus. This is caused by an auto-antibody triggered by streptococcus bacteria in certain people. The susceptibility to have an autoimmune reaction is likely inherited as well.
They Can Be. Motor tics can occur more commonly in families. However, there are many situations in which this is not the case.