Actually, in your country sex between two step-siblings is not illegal. It is defined as sex, whether heterosexual or homosexual, between a person and their parent, grandparent, child, grandchild, sibling, half-sibling, uncle, aunt, nephew or niece. It is punishable with up to 14 years imprisonment. There is no step-sibling mentioned, and therefore is not illegal. Now, if we were to go by the law of the place the state is based on (Ohio, my home state) it still isn't illegal. Because in Ohio, the laws against incest only involve parent and child relationships. It's still legal for a brother and sister or two brothers to do it.