Interesting study. Three gay guys that come to mind first (who I know personally) all have at least one older brother. Come to think of it they're also the youngest.
"Men with older brothers more likely to be gay"
http://news.yahoo.com/s/ap/20060626/ap_on_he_me/sexual_orientation
" WASHINGTON - Having several older brothers increases the likelihood of a man being gay, a finding researchers say adds weight to the idea that there is a biological basis for sexual orientation.
...
The increase in the likelihood of being gay was seen only in those whose brothers had the same mothers, whether they were raised together or not, he said.
Men raised with several older step- or adopted brothers do not have an increased chance of being gay."