Punish rapists severely

Editor,I read with awe the story in The New Times where a 33- year-old man was arrested for allegedly raping his own 11-year old daughter. If the investigations confirm that this man indeed sexually abused his own daughter, he should be heavily punished. What could make a man rape his own daughter? Is he sick? I think doctors should also examine him for insanity. Recently, I read a book- Lord of Flies by William Golding which explains that man is evil by nature.