Psychic son?

My son is 3 years old and 3 weeks ago he turned to me and his dad and said "mummy there's a baby in your tummy and it's saying boo to me, it's my baby sister" thinking nothing of it I brushed it off until this week when I took a test and found out that I'm pregnant!! He has now started saying to me that he can see baby twins and two babies in there! He keep pouring out two cups of water for 'the babies' just another 6 weeks before we see if he's right or not :) might explain this damn backache!!!!!!!!!