This book which was written by Lawrence Wright really answers many of the questions about human cloning. the book focuses on identical twins separated at birth and how they shared many similarities even after being raised in entirely different enviroments.
With human cloning, you are actually bringing a later born twin into the world. There has been a "nature versus nurture" debate raging for many years. Every person has a different idea as to how much we are a product of our genes and how much we are a product of our environment.
When human cloning becomes commonplace, many of those questions will be answered. That is why the study of identical twins is highly relevant to the study of cloning.
Just reading the postings by identical twins at web sites like www.TwinStuff.com can be illuminating. It will make almost anyone desparately wish that they had the good fortune in life of having had an identical twin. Human cloning is as close as we can come to achieving that dream.