My 17 month old granddaughter is scared every time anyone enters the house, including people she knows. As soon as anyone comes in she runs to her mum crying, she also looks frightened. She clings to her mum and if the person who has entered talks to her she cries more. After around 20 minutes she will slowly leave mum and carry on with whatever she was doing, then eventually will be comfortable with the person and happily sit with them or play.
Any ideas why she reacts this way?