Interesting fact:

Birth can influence your personality. It’s a common theory that your position in the family, ultimately, shapes how you grow as a person. Older siblings tend to be “responsible”, “decisive” and “independent,” whereas the younger child is often described as “impulsive” and “wild.” One study even found that your role in the family can affect your romantic decisions, with first-borns often pairing up with other first-borns, middle children with middle children and last-borns with last-borns.