In a study of over three hundred undergraduates (sets of siblings), the researchers found that firstborn siblings were significantly more likely to have Get-Better goals and use self-referenced standards, than secondborns.

FORBES: How Firstborns and Secondborns Compare

Some of the kids he interviewed referenced hallucinations, suicidal thoughts and self-harm, all driven by the fact that they were so utterly and torturously alone under these conditions.

CNN: No kid should be in solitary confinement