Since My Daughter was 2 she had Unusual Habits

Parents find many habits and behaviors of their children annoying. When you want to change an unwanted behavior, it helps to first understand why your child is doing it. Often bad habits are just a coping strategy. Your child may fall back on these behaviors when they are stressed, bored, tired, frustrated, unhappy, insecure, or falling asleep. Many of these “bad” habits are calming and soothing to the child.

Most of the time, these behaviors are just “phases” or habits—not serious medical problems—and the child typically outgrows them. Managing them can be difficult, however. In general, you should ignore bad habits. Yelling, calling attention to the habit and punishment do not usually work to stop the behavior (and may even increase it!), but praise, positive rewards, and patience are likely to help.

First, try ignoring the annoying behavior. Your child will probably outgrow the habit with time. Giving a lot of attention (even though it's negative) may actually encourage the behavior.

Praise your child for good behavior. The best kind of praise simply describes what you see that you'd like to see more of. Catch your child being good, and tell them you noticed. For example, tell them you noticed they weren't chewing their nails.
It may be nearly impossible to stop the bad habit until the child becomes interested in stopping. For example, a little girl may actually get enough “benefit” out of biting her nails that she will not be willing to stop. When she gets a little older, though, she may be interested in having nice looking nails. Then you will be able to help her quit.
If there are lots of behaviors you want to change, start by focusing on one or two of the most bothersome or dangerous ones. Don't try to make too many changes all at once.

Try to figure out what may be making your child stressed, and help them deal with it. Give your child chances to talk to you about things that might be worrying them—make eye contact and actively listen.

Let your child make decisions whenever possible, by giving them acceptable choices. For example, “Would you rather have toast or cereal for breakfast?” This will help your child feel in control, reducing stress and frustration.

Redirect your child and help them find a better place, or better way to do what they are trying to do. For example, if their nose is irritated, have them clean it with a tissue, apply saline nasal spray or petroleum jelly (consult your pediatrician for their recommendation), and then wash their hands. If they simply must go “digging,” have them do it in the bathroom, not in public, and wash their hands afterward.

Use natural or logical consequences for problem behavior. The purpose here is to get kids to make the right decision, not to bend them to your will. Be patient—it may take time for you to see results.

Be firm and kind. Follow through every time on the natural or logical consequences.
Have a few positively stated rules, and explain the reasons behind them.
Make sure your child understands the results of breaking the rules.

http://www.askdrsears.com/html/6/T061300.asp

It sounds like a habit to me too, but one thing I was thinking about that hasn't been suggesed yet, and may be at least something for you to consider is a condition called Pica:

http://www.kidshealth.org/parent/emotions/behavior/pica.html

I never had craving when I was pregnant, but a friend of mine had pica where she wanted to eat dirt and SHE chewed on plastic things all of the time. I went and looked it up and it seems like it could be a childhood issue as well. It may be worth a chat with your doctor.

Yes, pica could be a problem here, and I did consider autism in this case, but not enough info to go on really.

Jodi, what I don't think of, you do, and vice versa, we should be the dream team LOL