DS (13 months) has been biting for the past month or so. It's only been me or DP he does it with, my mum looks after him x2 a week and he goes to a childminder another day and it has never happened with them. Apart from this he's a happy, sociable and quite easy going boy. It's not constant, but it is quite regular. He does it when he's excited/joking about and laughing and also when he's upset/angry. An example from today is he was standing at his activity table and lost his balance and fell, he was upset so I picked him up and he got annoyed with me and bit my shoulder. Is this something to be concerned about? He does it with his toys aswell sometimes so I'm wondering if it's a sensory thing? He is my first so I really don't have much experience around what's normal toddler behavior and what's concerning.