My ds (14mths) is a lovely little boy but we have a problem with him biting, and more recently grabbing peoples faces. He is not doing this aggressively, I think it's his idea of trying to play, but it's becoming a real problem in playgroups. Today he grabbed at 5 other children (and made them cry) and I felt v upset and mortified. My efforts to get him to stop seemed to goad him on to more bad behaviour.
When he does it to me, I have been saying a firm 'no biting' and then walking away from him for about 30 secs. This worked well initially, and he definitely bites a lot less now, but then he took up grabbing. He seems to be getting less upset by me walking out and almost treats it like a game. I'm wondering if he's just too young for it. He's a very confident character, and is completely unfazed by a stern voice.