Some studies suggest that singletons do better academically and socially than children with siblings, but there are others that show the exact opposite. That's science for you!
"There's no question that being an only child is very different," says Shaw. "It does come down to parenting again. If you're a parent of (multiple children) one of the biggest issues is setting limits… You have to draw a line in the sand… and enforce the same rules for all children. Otherwise they feel like this or that is unfair because the younger or older one didn't get it, which can have long-term effects."
Otherwise, birth order probably isn't a big deal
One of the most comprehensive recent studies on birth order reviewed data on more than 20,000 adults from the United States, the UK, and Germany. Researchers focused on what's known as the "big five" personality traits -- extroversion, emotional stability, agreeableness, conscientiousness, and openness to experience -- to reach the bright, shiny conclusion that birth order doesn't have any influence on personality after all.