There was a book I read in the 80's called Healing The Family Tree by Dr Kenneth McCall. Many miracles were cited. One of which was about twins separated at birth. Both had the same serious debilitating condition unbeknownst to the other. One lived in the UK one in US. McCall was assisting the one in the UK. Following a prayer service for the forgiveness of specific sins of her forefathers the Uk twin was miraculously healed. Years later the twins found each other only to discover that the US twin was healed at exactly the same time without any knowledge of earlier events. Prayer is enormously powerful even when we don't see its fruits.