system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do monarch butterflies migrate through multiple generations, considering that one of them can only make it part of the way?
gpt
Genetically learned traits. Basically they've been doing it so long it's become ingrained in their core. They even fly around an obsticle (can't remeber if it was a mountain or lake) that's not even there any more! A million (or whatever) years ago this feature of the Earth went away, but the butterflies still circle where it once was.