Ok , my 8 month old twin grandson has discovered he can voluntarily tense his whole body and smile at the same time . He is doing it more and more . I think he has discovered it gets him attention and his mom is really worried about a CP hypertonicity disorder . He is not sucky like his brother even when he just got his first tooth today and a very happy baby. The only bad thing about him is he doesn't sleep well at all waking at least 8 times a night and a very light sleeper . Eats everything well . What do you think about the tensing of his body ?