Although people with cross eyes are born to be, it can be natured by the future habit of using eyes. Thus, you should not imitate this habit. Once the habit is kept into form, you will get this in an unconscious way which will be difficult to be corrected. Thus, not do this. Or your eyes may get the problems.
Cross-eyed is also named esotropia. The eyes muscle disorders and nerve muscles paralysis will possiblely cause the cross-eyed. As your eyes are wholesome, you may like to make the cross-eyed. I would like to persuade you give away this movement if no need. If this kind of gesture continue for some a long time or often does, your eyes muscle will be used to disordered and the nerve muscles will lose the balance. If you are not a actor, you would better do good to your eyes and keep it functional with normal use.