They aren’t real siblings. She was adopted.
http://www.mangago.zone/read-manga/death_is_the_only_ending_for_the_villainess/uu/mpn_chapter-2297645/pg-5/
that's penelope. im talking about the original heroine, yvonne. lmao
My bad! Sorry! But rest assured, there isn’t any incest with Yvonne either.
http://www.mangago.zone/read-manga/death_is_the_only_ending_for_the_villainess/uu/mpn_chapter-2299489/pg-2/
ooh I kinda interpreted that part to say "she was meant to be a happy family with them either way, that's why they're the easiest capture targets." I'd be happy if it were to be interpreted that their route leads to a happy family tho (even when it doesn't matter haha), since "receiv[ing] a confession of love and obtain[ing] an [romantic] ending" from siblings is a big nono lololol
i just realized..... when yvonne reaches full favorability w her brothers... she gets a love confession......... her real brothers, not even step siblings......