[orion]

Originally Posted by 7Th

No, no.

Spoiler for Episode 24:

"They" don't come from a different planet, they were "created" by the meteor when it fell on Earth; it exploded in Dark and Light Cosmo and it gave birth to two lives: Kouga and Aria.

Spoiler:

But...you really can't assign kinship until you do genetic testing. Aria was influenced by Athena however she resembles Eden so we have the Mars predominence. Koga's influence by Athena and looking like Seiya (a human) means that the genetics are now different for those 2.Too far to be considered sibs imo.

If you're really conservative about this, they could be considered step-siblings. Even with step-sibs if they aren't raised together and the genetics aren't there, then it's apparently fair game to be in a relationship.