A study conducted by Jeannie S. Kidwell, explored the self-esteem of middleborns compared to first and last born children. The key aspects of this study included variables such as the number of children, spacing in age, and gender. Kidwell wanted to study Middleborns compared to firstborns and lastborns in relation to Self-esteem. This is because she believed self esteem is an important scope of one's identity and is related to many other areas of competence, achievement, and relationships during a child's development. The study found that self-esteem decreases as the number of siblings increases but is only noteworthy when the siblings are spaced at an average interval of two years. The study suggests that this is because “there is less time to develop and solidify the uniqueness inherent in being firstborn and lastborn when there is only one year between siblings. With this compact spacing, all three birth positions become less distinct, clouding the behavioral and perceptual differences between them.” This uniqueness is referred to as the “lack of uniqueness” phenomenon. Which is defined as achieving status, affection, and recognition among siblings and feeling special in the eyes of one's parents. Which Kidwell was testing to see if this was more difficult for the middleborn and is reflected in overall self-assessment. Kidwell also determined through this study that being an only male among female siblings creates a much higher form of self-esteem, helping to balance the lack of status which occurs when one is caught "in the middle.”
