How do some plants that are unrelated have such similar flavors?

Coincidentally similar chemical structures of by- or co-products of their metabolism.

Probably.

@The_Idler has it right. Simply a case of convergent evolution, or an old ancestor in common.

Many different creatures share very similar metabolisms, even though they haven’t been related for millennia. Take the simple fact that most multicellular creatures have oxygen-based metabolisms.

On the other hand, it’s possible that they’re totally unrelated, but happened to have evolved to use or create the same substance. This is convergent evolution, and happens quite a lot.

So, the plants you’re referring to probably either have some ancestral link to some similar metabolite that is causing the taste similarity, or have a convergent evolution onto the same or similar metabolite.

People and insects both have eyes. Successful evolutionary ideas can develop independently. This applies to unrelated plants as well. Unrelated of course means distantly related. All life is related.

This probably isn’t directly related, but this topic reminded me of it, and even though I can’t really draw any intelligent connections, something keeps bugging me that it can be somehow relevant.

@Dan_DeColumna Possibly the theories on that show of how there are so many humanoid worlds, the two being either convergent evolution, which i brought up, or a ‘seeding’ by a much older species, which I think ended up coming true.

@BhacSsylan: Thank you.