What offense is committed if Alex engages in sexual conduct with their adopted sibling?

The offense committed in this scenario is described as "prohibited sexual conduct." This term generally encompasses sexual relations between individuals who are closely related, including situations involving adopted siblings. In many jurisdictions, engaging in sexual conduct with an adopted sibling is classified as a criminal behavior because it disregards societal norms regarding familial relationships, regardless of whether the individuals share biological ties.

The law aims to protect family structures and prevent potential abuse that could arise within these dynamics, as the familial bond—even in cases of adoption—can create a power imbalance and emotional complications. Therefore, the behavior of engaging in sexual conduct within this context is specifically addressed under statutes related to prohibited sexual conduct, as it poses risks to the safety and integrity of familial relationships.

Other options, although related to offenses concerning sexual conduct or relationships, do not accurately describe Alex's actions based on the context provided.