Also why.
Sure there will always be some people who want to explore for exploration’s sake. But a generation ship leaving a garden of Eden we’re quite literally built for in order for our children’s grand^(1000)children to terraform a rock half a galaxy away in order to have a different mix of resources?
That’s a hard sell for the first generation, to say nothing of those who come after.
I would expect indoctrination something like what keeps alignment among devout religious practitioners would be forced to emerge. The alternative is extinction on a spaceship hurtling into the vastness of space.
I suspect education on that ship would look a lot different than it does on Earth.