6 years, 1 months.
Back in college, I was really into this book called The Birth Order Connection. It explains the theory of how our personalities are ultimately guided by what order we were born in the family.
It describes how an “only child” is different than a first-born child; but if a first-born child is at least 6 years-old when the 2nd sibling is born, both children ultimately become more like only children because those earlier formative years are not shared with another sibling of the same age.
When I Googled “traits of an only child” just now, here’s the first thing that came up:
“Only children, being firstborn themselves, tend to exhibit traits more similar to those of other firstborn children. However, only children seem to have better self-esteem and are higher achievers than children who have siblings (Brophy, 1989, p. 54).”
When your sister was born, you were about 5 and a half years-old; to be exact, 7 months shy of that 6 year-old mark. So really, you’re borderline on whether you will adopt a first born (older brother) mentality as opposed to an only child mentality.
And then same can be said for your sister, as long as no more siblings are born within the next 5 years. In theory, she may never really develop the mentality of “younger sister”. Instead, the two of you could easily both end up having that ultra-independent personality of an only child.
After all, the two of you will never really have to share your toys with each other. The two of you get to live next to each other, but always in different stages of childhood development.
Earlier this week on the drive to school, I told you, “Jack, when Holly’s your age now, you’ll be 11 years-old; you’ll be finishing up 5th grade when your sister turns 6; the age you are now.”
You laughed at the thought of it.
But that’s the reality. You are her older brother and she is your younger sister, but really the two of you may end up technically more like only children.