The topic of birth order and its impact on personality development has fascinated people for decades (Alfred Adler, a Freudian-era psychologist gets credit for the original theory), probably because it is something to which all can relate. The New York Times featured an interesting article this week by Dr. Perri Klass on the topic of birth order and its relevance. Check out the article here: http://www.nytimes.com/2009/09/08/health/08klas.html
As the article points out, using birth order to classify personality can become something like predicting relationship patterns using astrology. However, the article elucidates two important factors in personality development: family dynamics, and temperament. Being the firstborn child does not "make" you strong-willed and a natural leader (or "bossy" as my little brother would put it), but parents are often more likely to treat a firstborn child in such a way that influences him to develop into a leader. Likewise, parents may be more likely to coddle the baby of the family, which could influence her to become more dependent. However, as the article points out, temperament can sometimes trump all. If a firstborn has a reserved, shy temperament, then she may never develop into a strong-willed leader, no matter how her parents treat her. Thus, the nature versus nurture debate that pervades psychology arises once again. Are temperament and early family dynamics equal players in personality development, or do they impact different people in varying proportions? As a firstborn child with an extraverted, outgoing temperament who developed into a strong-willed, independent woman prone to taking on leadership positions, in my case, I'd say its fifty-fifty. What do you think?