On a general level, I’m #4 of 5. On a more specific level, I have two older half-brothers and an adopted older sister. I was the youngest until I was almost 14 when my younger half-sister was born. So simultaneously, I’m #4 of 5, #3 of 4, and an only child.
Me too - I call myself a double middle (except I had two older sisters and two younger sisters).
I’m an only child, and a totally typical one.
I’m the younger of two boys.
Youngest of 5. I was hoping someone would tell me what birth orders are supposed to mean instead of making me do my own homework (hmph), but nope. Quick overview here. I’d say it’s about as accurate as a horoscope.
Middle of 3 boys.
The description in MeanOldLady’s link is eerily spot-on for a paragraph and two sentences, but then goes wrong at the bullying part and afterward.
I’d say these sorts of things are over-generalized and certainly don’t take everyone’s individual circumstances into account, but they at least have a bit of a link to reality, unlike horoscopes which are just made up out of thin air.
True, atrology was created out of nothing by a bunch of assholes, but thinking about my family, this may as well have been dreamt up from whole cloth. The idea of my oldest brother being “responsible” or “task-oriented” is too wildly off-base to even make me laugh. My sister is a classic middle child attention whore, so they get one point for that, but then lose another as reading the description of the last born is like reading a description of someone I’ve never met. Total score: -1. I read my horoscope for today just for kicks, and I had no idea what it was supposed to mean which I scored as -1, so yup, they’re tied in terms of accuracy.
I’m the older of two with a third child stillborn, making my younger brother either younger or middle, depending.
I’m the fifth in a line of oldest-son of oldest-son and my oldest son’s first (only) child is a girl, stopping that sequence.
I’m the second of six, in a BGGBGG pattern. My older brother is kind of absent, so, functionally, I’m an oldest. What I find interesting is that we’re in two very distinct cohorts - gaps of two years each between the first three, then a four year gap, and then two year gaps between each of the second three. My younger sibs grew up in a household that was radically different from mine, without any change in family composition.
I’m the eldest of three and the only girl. Brothers are twins born 364 days after I was born.
I’m the middle of three.
Me too.
Oldest, but my half brother is 17 years younger so I was an only child almost til college. Although I had an unofficial stepbrother of sorts my own age at my non custodial parents house.
I almost posted something like that (went back and forth a few times), but each web site will have slightly different takes, there’s a lot of controversy and debate surrounding birth order’s putative effects, and I didn’t want to derail my thread by having a bunch of people arguing about it here. If you wish to start a new thread in GD, knock yourself out.
Only child, but have step-siblings I met by 4th grade, became formally related to by 6th grade and lived with from 8th grade. One was roughly my age, the other two years older.
Briefly had a third, a much younger step-sister I never lived with, who I am out of contact with and haven’t seen in ~25 years.
Or they suck at following it/them…
Aww, you’re the baby of the family!
Yes, you may punch me for that.
I’m an only child, but I’ve had assortments of step-siblings that changed up my birth-order for significant periods of time. I was the oldest for 8 years and shared a bedroom with two younger sisters (also had a younger brother.) Prior to that I was the oldest to a stepbrother and stepsister for 2-3 years, prior to that I was the youngest of three girls for about a year. I also have a half-sister who was born when I was about ten, but we had no regular contact.
Also, my Aunts and Uncle weren’t much older than me… my Aunt is four years older and my Uncle five, and I practically lived with them growing up so I’m very much the ‘‘youngest sibling’’ in that context.
I’ve been everything, then. But personality-wise I’m still a classic only child. I was the only grandchild for 15 years. Spoiled as hell, highly introverted and perfectly capable of entertaining myself. 
Yeah, that’s my situation, kinda. Youngest, my brother is 10 years older than me. He was pretty independent, so even as a teenager he’d be gone for work every night. I figure after kindergarten I became the only of the family.
It’s still worked out pretty well for us, we never had sibling rivalry. We both grew up around lots of adults and not so many kids and were more mature because of it.
Not to hijack but Dopers who are married/otherwise partnered …
What is your birth order and your spouse/partner’s birth order?
“They” say to marry outside your birth order. Two onlies are bad news and an only with an eldest is almost as bad. Babies should marry middles or eldests, etc.
I’m am only married to an eldest. It works, though.
It’d be interesting to see how many of us ended up with people outside our birth order and if the difference can even be seen in the relationship.