Frequently Asked Questions About Birth Order
Even with the modern scientific consensus, the allure of birth order theory leads to many persistent questions. Here are a few common ones, addressed with a blend of historical context and current research.
Does birth order affect intelligence?
This is one of the most studied aspects of birth order. The answer is a qualified “barely.” Some very large studies have found a small, statistically significant correlation where firstborns score, on average, one or two IQ points higher than their later-born siblings. However, this is an average across hundreds of thousands of people. On an individual level, the difference is completely meaningless. You will never be able to tell who is a firstborn based on their intelligence. The leading theory for this tiny effect is the “tutor effect”—older siblings often informally teach their younger siblings, which reinforces their own understanding and cognitive skills.
What about twins or adopted children?
These situations beautifully illustrate the limitations of simple birth order rules. Twins occupy the same birth order slot, yet they almost always develop distinct personalities and roles within their dyad (e.g., “the quiet one,” “the outgoing one”). Their unique relationship with each other is a far more powerful shaping force than their birth order.
For adopted children, the environment they are adopted into—the parenting style, socioeconomic status, and emotional climate of their new family—overwhelms any theoretical effect of their birth order in their biological family. Their experience highlights the profound power of nurture and environment in shaping personality.
Is birth order theory still taught in psychology?
Yes, but primarily as a topic in the history of psychology. It’s important for students to understand Alfred Adler’s contributions and how his ideas influenced later theories of personality and family therapy. However, it is not taught as a valid, predictive model for understanding an individual’s core personality traits in the way the Big Five model is. It is presented as an early, intuitive attempt to explain human differences that has since been superseded by more complex and empirically supported theories. It’s a foundational concept, not a modern diagnostic tool.
