Does Birth Order Make a Difference?

I am an only child. When I mention that to people for the first time, occasionally someone will mention something about only children being quieter or more independent. I've always wondered if there was actual merit to this, and if birth order actually permanently influenced behavior or personality.

There are distinct stereotypes found when it comes birth order. The oldest child tends to be more authoritative and competent. The youngest tends to be charming and popular, and capable of getting others to do what they want. The middle child tends to feel forgotten and overlooked, while only children feel constantly scrutinized and pressured.

There is one interesting caveat to studying the effect of birth order- a child's "actual birth order" may differ from their "perceived birth order". This can occur due to illness within the family, the size of the family, or significant age differences between siblings. Studies have found that your perceived place within the family actually does influence the beliefs of individuals. Furthermore, a study performed by a Ghent University psychologist found that, on average, siblings close in age (roughly 2.5 years apart) set goals differently. First-born children were significantly more likely to choose goals that that were "self-referenced" (more likely to be chosen for themselves) while second-born children were more likely to choose goals that were "other-referenced".

While there does seem to be some veracity to the assumptions we make about birth order, differences in first born children, second born children, etc. could emerge simply because parents subtly project these roles onto their children. By being treated as the authority figure by their parents, acknowledging the popular stereotype, the first born may assume this role. It's funny to think that maybe our "pop psychology" assumptions may influence behavior, instead of the other way around.

(SOURCE: http://www.psychologytoday.com/blog/fulfillment-any-age/201305/elusive-birth-order-effect-and-what-it-means-you)