Bowen theory incorporates the research of psychologist Walter Toman as a foundation for its concept of sibling position. Bowen observed the impact of sibling position on development and behavior in his family research. However, he found Toman's work so thorough and consistent with his ideas that he incorporated it into his theory. The basic idea is that people who grow up in the same sibling position predictably have important common characteristics. For example, oldest children tend to gravitate to leadership positions and youngest children often prefer to be followers. The characteristics of one position are not "better" than those of another position, but are complementary. For example, a boss who is an oldest child may work unusually well with a first assistant who is a youngest child. Youngest children may like to be in charge, but their leadership style typically differs from an oldest's style.
Toman's research showed that spouses' sibling positions affect the chance of their divorcing. For example, if an older brother of a younger sister marries a younger sister of an older brother, less chance of a divorce exists than if an older brother of a brother marries an older sister of a sister. The sibling or rank positions are complementary in the first case and each spouse is familiar with living with someone of the opposite sex. In the second case, however, the rank positions are not complementary and neither spouse grew up with a member of the opposite sex. An older brother of a brother and an older sister of a sister are prone to battle over who is in charge; two youngest children are prone to struggle over who gets to lean on whom.
People in the same sibling position, of course, exhibit marked differences in functioning. The concept of differentiation can explain some of the differences. For example, rather than being comfortable with responsibility and leadership, an oldest child who is anxiously focused on may grow up to be markedly indecisive and highly reactive to expectations. Consequently, his younger brother may become a "functional oldest," filling a void in the family system. He is the chronologically younger child, but develops more characteristics of an oldest child than his older brother. A youngest child who is anxiously focused on may become an unusually helpless and demanding person. In contrast, two mature youngest children may cooperate extremely effectively in a marriage and be at very low risk for a divorce.
Middle children exhibit the functional characteristics of two sibling positions. For example, if a girl has an older brother and a younger sister, she usually has some of the characteristics of both a younger sister of a brother and an older sister of a sister. The sibling positions of a person's parents are also important to consider. An oldest child whose parents are both youngests encounters a different set of parental expectations than an oldest child whose parents are both oldests.
Knowledge of Michael and Martha's sibling positions and those of their parents adds to the understanding of how things played out in their lives. Martha is the youngest of three girls and was the most intensely focused on child in her family. Furthermore, Martha's mother is the oldest of four siblings and was raised in a family with a mother who was a chronic invalid. Martha's mother was a not very well differentiated oldest daughter. Her life energy focused on taking care of and directing others to the point that she unwittingly undermined the functioning of her youngest daughter. Martha played out the opposite side of the problem by becoming an indecisive, helpless, and mostly self-blaming person. Martha's father was the youngest brother in a family of five children.
[Analysis: Martha, by virtue of her mother's focus on her, has the moderately exaggerated traits of a youngest child. Furthermore, her father being a youngest and her mother an oldest favored her mother's functioning setting the tone in the family. In other words, her mother was quicker to act than her father in face of problems.]
Michael is an only child who, like Martha's mother, was raised in a family with a mother who had many problems. Michael's father is the younger brother of a sister and his mother is the older sister of a brother. Michael's mother was the more focused on child when she was growing up, a focus that took the form of high performance expectations coupled with considerable family anxiety about her ability to meet those expectations. In many ways, Michael's father was quite dependent on his wife for affirmation and direction, even when she was depressed and overwhelmed. As an only child, the pattern of functioning of the triangle with his parents was the major influence on Michael's development. His emotional programming in that triangle made him a perfect fit with Martha.
[Analysis: Michael's only child position makes him a somewhat reluctant leader in his nuclear family. He wants Martha to function better and to take more responsibility. He is unhappy feeling the pressure himself. Despite being in the one-up position in the marriage, he is as dependent on Martha as his father was dependent on his wife.]