I am also one of three children.
Oldest (My sister)
Doesnt' fit the description at all, or maybe she just went the path of disappointment and followed it, it stead of always striving for perfection. Part of it may be due to her being from a previous marriage of my mother's, and having my father come into her life when she was about 3. She lost her virginity around 13 or 14, frequently spent days or weeks away from home with boyfriends. She's been addicted to multiple types of drugs, and currently at 31 has alchohol issues. She's gotten pregnant unintentionally twice. The first time resulted in a funeral for a two-month-old, thanks to drug use. The second one resulted in rushed marriage that lasted 6 months, and then left my sister living with mommy and daddy again, with her baby.
Middle (me)
I'm sure this is gonna seem skewed, since it's me writing it, but I fit the "left out in the cold" middle child description perfectly. I never feel like I'm noticed or cared about, in any relationship, ever. That goes for romantic relationships, friendships, coworkers/employers, family, everything. I wear wild hairstyles and piercings because I absolutely hate the idea of looking "normal" or "fitting in". I'm lazy, I never finish what I start, and I can't stand being around most people. Anyone who's seen one of my "my life sucks" posts knows all this probably.
Youngest (my brother)
Yes, he's still mommy's little boy. He's much closer to our mother than me or my sister. He can't stand the idea of moving far away from her, and he's the only one of us three who has never moved out of the house (me and my sister have both left and come back). He is extremely shy and antisocial (not like me though, he is more afraid of people). He was recently diagnosed with 4 different mental disorders related to him being antisocial and stressing out about being around other people. (the only one I remember was agoraphobia, which was supposed to be more about him fearing uncontrollable situations than really being afraid of open spaces.)
So I fit the middle child description, my brother kind of fits the youngest child one, and my sister isn't even close to the first born one. Again though, that may be due to the conflict between her and my dad, due to him not being her birth father.