With habits, as with many child health issues, there's a fine line between normal development and something that requires attention. While habits are normal, a tic might be a symptom of a health problem. So how do you tell them apart? For starters, a habit is more of a behavior or practice, while a tic is a repeated contraction of certain muscles and can't be voluntarily controlled much of the time. Most tics last for less than a year, but they affect up to 20 percent of kids -- boys much more frequently than girls. Sometimes tics come in the form of muscle patterns (excessive blinking, for example), and sometimes they can be verbal (the child making a certain sound over and over). After the age of two or three, echolalia -- when a child repeats sounds made by another person -- can be a sign of autism, Tourette's syndrome, or another disorder. However, it's quite normal for kids to repeat babbles and words earlier on, when they're starting to put words together.
More Answers from Mehmet Oz, MD