Both of my children display unusual characteristics when excited

My children are 9 (girl) and 5 (boy) and both of them present unusual facial and motor characteristics frequently during the day when they become excited or fixated on a particular subject. I myself who am now 40 have always displayed a similar affliction since childhood. It would be an easy diagnosis to suggest that they simply copy their father and have conditioned themselves to my own behaviour but I am convinced that this is not the case as they both present their affliction in very different presentations. My son raises both fists to his cheeks and utters nonsense through clenched jaws while often going crosseyed and exerting such intensity that he often shakes and is quite breathless at the end of each episode. I have considered some type of epilepsy but now doubt this as he will respond and immediately calm down if you address him. My daughter also expresses a grinding of the jaw but not so intense as my son and will twist her fingers into extreme double jointed patterns. She also shakes but not as intense as her brother. If they were copying me then why do we present three totally different characteristics? A couple of years ago a Paediatrician suggested that it would pass in time and not worry too much but unfortunately it seems to be getting worse and both children have now reported that their peers at school are making comments which are upsetting, particularly my daughter who is approaching the age where other children can be inestimably cruel.  We are scheduling a meeting with the school headmistress and are hopeful that her experience will shed light on the phenomena. already the children are mentioning that the teachers are trying to encourage both of them to abstain from their 'Habits?' but if this is a more deeply rooted problem then I feel that telling them to stop could exasibate the condition and potentially affect their confidence. I have heard that children who demonstrate high intelligence are prone to similar behaviour. My children are hardly back of the classroom students but conversly, I have no plans to enter them into MENSA just yet! Any thoughts???