Personality measurements for ascendancy, emotional stability, responsibility, sociability, and self-esteem were compared across birth order categories. Undergraduates reported whether they were the eldest, middle, or youngest children of their families, only children, or of inconsistent birth order due to parents' remarriage. ANOVA [a statistical procedure] did not support any significant effects for these personality traits across birth order categories for either males or females. It was concluded that the hypothesized differences must be relegated to folklore [i.e., superstition].
PsychoHeresy Awareness Letter, Sept-Oct 2002)
[TBC: Birth order psychology is prevalent among Christian psychotherapists.]