A lot of reference to that sadly.
SPOILER BELOW
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MC (Ahrin) obsessed with getting her stepmothers (Anna) supposedly motherly love it's borderline incestuous. Ahrin kissed Anna on multiple occasion to test her power (she can momentarily controls men she kissed but not woman). But as the story progressed Anna began to realize Ahrin is the only one in the family who never treats her in the outdated patriarchal view unlike the rest of the men in her family.
MC's adoptive brother (Sion) who's same age as her seems to genuinely love her as a woman. Meanwhile I think MC views him as family because in that house Sion is the only ally she ever had and treats him as special.
MC's other adoptive brother (Siyoon) was hypnotized once but the effect lingers on him and he's convinced he's her true love. He's mainly serve as comedy relieve, sad.
Meanwhile Anna is object of hopeless romantic of her own stepson (Sihoo). He's son from previous wife (deceased) so he was practically raised by Anna. He's also conflicted about his forbidden feelings and trying to keep it to himself.
A lot of redflags but the plot itself is a total riot, incestuous element is just one of plot device among many other crazy things to stir the story wild. If you're uncomfortable with the idea at all you should avoid this.

Question sparked by the title. Is this incestuous?