As I was reading about an observation made about an infant star, I was suprised at the suprise expressed over what they saw. The star was surrounded by much more organic molecular material than expected. They surmised that ionized carbon was holding in the material, or there may be an abundance asteroids and comets containing the molecules in question.
Now, I had always asumed that earth was an acreation of many such aseroid and comet objects that would have brought to proto earth a consentration of molecules more simlar to a comet, but that the collision that resulted in the moon, also blew away many of the more unstable molecules, such as methane. So, wouldn,t we expect to find earth like planets around other stars that absent a great impact in its developement, would have a thicker atmosphere, with more of the more volitile gases.
Just a thought?