A pollutant which has increased with time for example. This would always affect younger brothers more, as a cohort, because they are inevitably born on average later on the pollution curve than their older brothers. Dan Craver after reading the first paragraph I knew it was wrong. My oldest Brother is gay. The first of the line. My cousin is gay and he’s the 2nd of that line. I have another cousin that is also gay and he’s the 1st born there too. I don’t think that the Coffee right meow shirt correlation is correct on what they are trying to prove. Besides I know I will catch some flack but homosexuality is a choice. Granted they may have been born feeling different but somewhere along the line, they made a choice. They have made a choice to give in to the feeling and just accept then who they are. Im not saying its a bad thing in the least. Most were driven to that choice and some have discovered that choice by themselves.