Not including your twin, of course.
Who is the person you’ve met or corresponded with who is very close to your age? My lifelong wish is to find someone born within an hour of me. The best I’ve done so far is norinew, nine days younger.
There are a few people at work who are around the same age as me to the year.
Kate Hudson (Godlie Hawn’s Daughter) was born on the same day as me.
When I was in school (elementary through high school) I knew several kids who shared a birthday with me, and they were in my grade, so I assume we were all born in the same year. I didn’t know them well enough to ask what TIME they were born, though.
As far as people I actually know well who are closest to me in age? My SO, for one, is three days younger, and my high school best friend, seven days younger.
I met a girl at a bar in my college town. I had just done a birthday shot - which she found was a coincidence since she was there celebrating her birthday as well.
We got to talking and it turns out that she was born about 15 feet from me about 45 mins after me. And this was the first time I had (theoretically I don’t rememeber if I looked at her the first time) seen her in 24 yrs.
It was pretty cool, but I haven’t talked to her since.
I knew a girl and actually dated her for a short time that was was born the day after me.
When I started high school, there was a father/son reception at the school one evening. My father recognized a guy he had hung out with in the expectant fathers’ waiting room at the hospital when I was born. So I went to high school with a guy who was born within an hour of me. I came first.
My next-door neighbor as a kid was born the day before me, but since I was born in the wee hours of the morning, we were actually only about 8 hours apart I think.
We were very close as little kids, and found the “almost twin” thing to be very cool. 
Baker and I share a birthday – I think we’re at least 12 hours apart, though. (I’m 6:10 AM, EST, if she shows up.)
My best friend in elementary school and junior high was born less than 24 hours before me, in the same hospital even.
I have a friend who is two days younger than I am.
I’m happy to say they aren’t Dopers, but my maternal grandparents were also born two days apart, in September of 1920.
My wife is 24 days younger than me. That’s as close as I can think of.
I share my birth date with Elza B
My husband is 12 days older than me, and I can’t think of anyone closer right now.
I learned back in the 1990’s that a colleague’s wife and I were born 30 minutes apart in February of 1965. I haven’t seen them in over a year, so this reminds me that I should give them a call.
Jammer
I also share a birthday with a fellow doper - TheShroud.
But, since he doesn’t have PM’s enabled I can’t ask him when he was born - or if it was even the same year.
I’ve met two people with the exact same birthday as me. One was just a friend of a friend of a friend that I met once and we never got into the time to the hour or anything.
The other was a guy I was in the theater group in college with. I can’t remember who was older, but we were born about two hours apart.
I used to know a girl, (her mom and my mom are/were friends) who was born 3 hours after me. Our parents met in the delivery room.
The wife of an friend and I share a birthday, although I’m not where we stand hours/minutes-wise.
I was born in Milwaukee on Feb. 5, 1970.
My best friend who lived 2 doors down from me was born the day before.
When we attended grade school there was another girl who shared the same birthday as me.
Actress Heather Graham was born 5 days before us also in Milwaukee.
I dated a girl for awhile that was eight days older then me. We kept in touch for a few years. A few years ago I knew a woman that worked at a photo shop that had the same birthday as the old girlfriend. I think those are the two closest people I know.