Is 'Eldest Daughter Syndrome' A Real Thing? A New Study May Surprise You.

Your oldest sister will feel so validated by this.

Growing up as the oldest sibling, author Y.L. Wolfe often felt the lines between her role and her mother’s role were blurred.

“By the time my youngest brother was born when I was almost 11, I was overwhelmed with feelings of responsibility for his welfare. I used to sit by his crib and watch him sleep just to make sure he was safe,” Wolfe, the oldest of four, told HuffPost.

“It wasn’t that I thought my mother wasn’t competent ― but more that I felt we were both responsible for the family by that point in my life,” she explained. “As if I was literally ‘other mom,’ rather than big sister.”

In other words, Wolfe is deeply familiar with “eldest daughter syndrome.” The internet is rife with thinkpieces about the plight of oldest daughters and tweets about how we ― I might as well reveal my bias here ― need to unionize: “If you are the oldest sibling and also a girl you may be entitled to financial compensation,” one woman joked on X, the platform formerly known as Twitter.

Though “eldest daughter syndrome” is a pop psychology term ― you won’t find it listed as an official diagnosis in the DSM-V ― a new study suggests that there may be more science to the pseudo-syndrome than previously thought.