Your birth order is far from your destiny
Since the 1920s, when Alfred Adler -- an Austrian psychiatrist and Freud follower -- introduced it as a significant factor affecting behavior and personality, birth order psychology's veracity has caused many disputes. That's why psychiatrists are still studying its effects, especially within familial twists like patchwork and single-parent units, and clans that have a lot of kids.
Basically, the Duggars would probably make for the wackiest possible study in birth order.
According to Daniel Shaw, a professor in the University of Pittsburgh's psychology department specializing in early development, the effect of birth order on personality is centered on parents, and how they help children navigate their spot in the family.
"What's important to remember about birth order theory is that it's not destiny," he says. "But order is in there somewhere. For example, we know that one of the issues, in a very primitive sense, is if kids grow up in poverty, the risk (of behavioral problems) raises with the number of kids. It's not to say if you're the oldest you're going to turn out being this way or that, but it does say something about resources."