National Geographic explains why identical twins might not have the same sexual orientation:
See web-only content:
http://www.theatlantic.com/daily-dish/archive/2009/11/same-genes-different-attractions/193632/
(Hat tip: Box Turtle)
This article available online at:
http://www.theatlantic.com/daily-dish/archive/2009/11/same-genes-different-attractions/193632/
