[davisfh]

I recall reading a science fiction novel that put forth this idea many, many years ago. Can’t remember how it ended, but somewhere along the way, the offspring of the many generations born during the voyage forgot what the mission was all about. The whole idea sounds implausible to me.

[danielmryan]

Sounds like Orphans of the Sky by Robert Heinlein. ("Universe", "Common Sense".)

[tbw2]

Gene Wolf's Book of the Long Sun

Robert Heinlein's classic Orphans of the Sky