Hi Tiffany!
Birth Order studies are controversial, and deal with studied "trends" rather than carved-in-stone "categories". Most agree that Birth Order is more a reflection of parents' expectations, rather than a child's personality. (You can look up "Birth Order" in wikipedia.)
The oldest child is supposed to be the most mature and intellectual, and many times is the sibling most "driven" to succeed. The oldest child is frequently treated as an adult by parents, who may confide or talk to them like a peer. So the oldest child is said to mature the fastest, and carries that over into a drive-to-succeed in their chosen profession. This is the child parents expect more from, according to Birth Order studies. Which sometimes takes the pressure off young siblings, who are more likely to be artistic, or go into professions that don't produce stock portfolios or homes in Tahiti.
For a long while, studies centered on the poor Middle Child. This sibling has to learn to "get what they want/need" around the youngest Social Butterfly and the oldest Driven To Succeed siblings. Thus the middle child many times makes an excellent Manager when grown, since they've learned to "negotiate" with vastly different personalities in their own family upbringing.
But, as I said, these are trends that don't always hold true. I'm the oldest sibling in my family, but I've always had more of an artistic personality. And, at 60, my bank balance certainly doesn't reflect any Drive To Succeed!
"I'm a writer. I give the truth scope." Chaucer (character) in movie "A Knight's Tale"
