Dad (One Small Step...)

The Dad and Mum of a little boy were nervous about letting him take a bath by himself. They watched Neil Armstrong walk on the Moon on television.

They were unaware that a timeline had existed in which their son had been hit by a car after speaking to the Second Doctor. After the Doctor went back in time to change this event, the family instead went to the beach for a barbecue. (PROSE: One Small Step)