Sibling sexual abuse includes penetration, touching, and other behaviors with sexual connotation that do not necessarily require touching. To differentiate sexual abuse from sexual curiosity or playing innocent games there needs to be coercion and domination over one sibling. Prevalence rates are also difficult to calculate for several reasons: victims do not realize that they are suffering abuse until they reach maturity and have a better understanding of the role they played during the encounters, they are afraid of reporting, and there is no consensus on a definition of sibling sexual abuse. Ryan writes how, "Child protection has focused on adult-child relationships, yet we know that more than 40% of all juvenile-perpetrated child sexual abuse is perpetrated in sibling relationships."