In-ho's mother never mentions whether he is adopted or a stepson in the original language.

In the original Korean version, Jun-ho's mother only says that she is not In-ho's biological mother. She does not mention whether he is a stepson or whether he was adopted. However, translations into other languages came out with confusing information that has not yet been explained in the work. For example, in English, German and other languages, they said that In-ho is Jun-Ho's mother's stepson. In Portuguese, they said that In-ho was an adopted son.

In other words, there is a lot of confusion in the information and that is why there is confusion in the fandom, since depending on the region where you watched the series, the translation came out differently.