When you give a girl a little sister, her whole world changes.
If you give a girl a sister, she will have a partner for life, no matter if she wants one or not. She will want to be as involved in her life as possible so her parents don't forget that she was their first daughter. She will secretly be happy she has someone to dress up with and help voice the other side of the Barbie dialogue although she will never admit it. But she will always make her sister play the parts she doesn't want to and be the Ginny to her Hermione.
When you give a girl a sister as a roommate, you are signing up for years of bickering once they become teenagers and you will be forced to get them separate bedrooms. She will always claim that her sister stole this shirt or hid this toy but will never tell you when she actually finds it under her own bed a week later.
She will also gain a copycat which will infuriate her at first because she wants to be her own person and won't understand that flattery is the highest form of praise. She will make her sister change instruments from flute to clarinet so she can maintain her individuality and throw a fit when her sister decides to try out for the cheerleading team too.
She will also learn how proud you can feel for someone else's accomplishments when her sister makes the cheerleading team and kicks butt at it. She will also become incredibly protective and threaten physical harm to anyone who even dares hurt her.
When you give a girl a sister, you also give her an a capella duet partner to sing to every song on long car rides and while loading the dishwasher. As well as a dance partner to come up with awesome new dance moves to perform for your family.
If you give a girl a sister that looks like her, she will constantly be told that they look a like but will get mad when they say that she looks like her sister, because actually her sister looks like her since she was born first.
And when the sister has to leave for college, she will experience heartbreak like no other because she is not just saying good bye to a sister but a best friend and partner for life.
