From the book The Talent Code, pages 115 and 116:
Usain Bolt: 2nd of 3 children
Asafa Powell: 6th of 6
Justin Gatlin: 4th of 4
Maurice Green: 4th of 4
Donovan Bailey: 3rd of 3
Leroy Burrell: 4th of 5
Carl Lewis: 3rd of 4
Leroy Burrell: 4th of 5
Carl Lewis: 3rd of 4
Calvin Smith: 6th of 8
It’s in reverse chronological order of world records, I believe, which is why Burrell and Lewis are listed twice.
And Ben Johnson was 5th of 6, as far as I can tell.
the implication being that if you are the first born then you won’t set a 100m WR? 
or if you’re parents have a lot of kids you might.
What was Montgomery?
There isn’t a definitive reason it has turned out this way so far. It could just be coincidence, of course.
The book speculated that it probably doesn’t hurt to hang out with an older crowd when you’re very young, and have to try to keep up. Being older and hanging out with a crowd your own age and younger probably doesn’t help, as far as giving you an incentive to be speedy.
I’m not saying it’s right, or that the pattern is even statistically significant. It was in the book I was reading, and I thought I’d share.
The reason could very well be less mineral bone density (ie smaller joints) as evidenced by the work of Weston A. Price DDS
what about, first child gets all the attention every other child gets tougher
along those lines, it’s interesting to note that marion jones used to compete against boys a lot when she was younger.
any such record available for female world record holders??
It was just one note in a book. So I have no idea if the results are similar for women. If the idea about “keeping up” is correct, I imagine having any brothers even close to the woman in age, whether younger or older, would help.
I have read a lot about top female basketball players. In virtually every case, they spent a lot of time playing with, and against, boys while growing up.
My dreams of breaking the Asian 100m & 200m WR shattered! 
On a more serious note, what if you’re an only child?
Surely the younger ones would get more attention instead.
To see how blatant “scientists” could be…all the example are of afro-americans families…I guess n1 implication is social…many women have their first born at young age., and a lot of sons too…sometimes the father disappears…or , in many event…the oldest sons have to work soon to give support.
There is a wide gap of age between sons many times in large families, and it happens last sons have less to care to mantain the family.Oh no…off course it is just genetic…I’d be interested to find out genetic differences in the sons of millionaire families playing sports…I guess none could be found…
Now i understand why the 3 fastest guys i coached didn’t broke the WR because they are elder brothers… I shouldn’t have wasted my time.
Yes Pj…I’m wasting my time too:)…I discovered a woman on a journal with 13 sons near here…I’ll try to adopt the latter and coach him|!
My wife is the last of 5 and she says her eldest sister got all the attention, coaching shoes and blokck. By the time she came along her parents were over it and she had to find her own way.
Guess it didn’t do the same for coaches. My guess it would be opposite
The Talent Code is actually a pretty good read
This seems somewhat related, and somewhat interesting, so I thought I’d pass it along.
http://www.nytimes.com/2010/05/25/science/25birth.html?ref=science