Board Thread:Theories and Speculation/@comment-32617252-20180630214116/@comment-1512913-20180701082221

The curse of hatred isn't an actual curse, or any other supernatural phenomenon. It's simply a feud that lasted for many generations.

And the workings are simple: 'our parents/siblings/friends hated, killed and got killed by the other clan, so we must too, to avenge them and honor their memory' Tracing its origins back to Asura and Indra. Started with daddy issues, but quickly became about revenge for murder of loved ones by the other clan, bscly.

But some could argue that curse of hatred was an actual supernatural phenomenon and it was specifically referring only to Indra and his descendants, with the curse being the Sharingan itself, but who knows.