Ishiki and Momoshiki are brothers

[Yahcob13]

Its just a hunch but their karma seals resonate. The seals Hagoromo gave Naruto and Sasuke resonated. This was because they were from the same source? Or maybe it was the energy between Ashura and Indra that caused this. Maybe both. This implies that Ishiki and Momoshiki share similar connections. Note that Kawaki's seal is on his right hand and Boruto's is on his left. I don't think this represents eyes and body or yin and yang. In my opinion it could only mean that they are two halves of the same being. Or they are brothers. We know that Otsutsuki have the ability to fuse with a ten tails. They can also fuse with each other the Momoshiki and Kinshiki did. If they can fuse perhaps they can also fission the way cells do. Im speaking purely hypothetically but what if there was an Otsutsuki who fused with a ten tails the way Kaguya did then split itself into multiple parts? I know it sounds far out but the full capability of the Otsutsuki are still unknown. But I like the idea of them being brothers and rivals a little better. It makes for an interesting backstory. So yeah I think they are brothers.

 

[salamander uchiha]

Could be

 

[Joon]

They are aliens. Besides, we need to compare the other Karma. If Kaguya was alive and it was shown her Karma was different then it would make sense that they were brothers, until then we don't know for sure.