The relationship between and among siblings is a study both intriguing and challenging. Many of us know the truth here firsthand from the experience of growing up in families. Even if one happens to be an only child, we are brought in touch with brothers and sisters in other families.

A great deal is made of the birth order in a family. For example, the oldest son has traditionally been known as the child who is to make his mark in the world and, in some cases, look after parents and those siblings who are younger. Frequently, the youngest child is seen as "the baby," who gets special privileges.

Oh, yes, we know the dynamics, don't we? Joys and sorrows abound. Successes and failures come and go. Tragedy and triumph are there to see. Who is the most successful? Who does mother/father lov…