The funny thing is the manga is arguing that becuase Naoomi was actually a secret child who was secret, that it is somehow more legitimate than an “open secret.” Yet, reading the manga here, now there is even more doubt on the half sibling MC’s that they aren’t blood. But it makes sense on some level this sense of distrust because characters have proven they lied and forged legal documents.
…and yes, this can be solved quickly with a DNA test that they are blood siblings.
Coward author, pretty sure they'll make the main pair not related now
Multiple people forging legal documents and they get away with a very illegal action should have planted the seeds of doubt a long time ago that they are blood.
The fact that they aren’t doing the easiest test to prove relations speaks volumes, and again, it can also be forged since we have seen the family has the capacity to lie on official, legal documents.