I grew up with all sorts of habits like that, so did my brother and sister, and now I see it in a friends daughter and my SIL (who is 11 and not blood related, so not running in family). It can be a type of anxiety, or control. It won't lead to OCD so don't worry (well it may occassionally but not in any of the above mentioned). I am no expert but I would say it's a habit. My mum used to give me three weeks (time it takes to break a habit) and then I'd get a reward. Maybe try that with her.
xo