Are you sure they are having sex? I ask because inappropriate things could refer to kissing to some parents. Which is not sex. Here are statutes that might help you:
§ 2907.01. Definitions.
As used in sections 2907.01 to 2907.37 of the Revised Code:
(A) "Sexual conduct" means vaginal intercourse between a male and female; anal intercourse, fellatio, and cunnilingus between persons regardless of sex; and, without privilege to do so, the insertion, however slight, of any part of the body or any instrument, apparatus, or other object into the vaginal or anal cavity of another. Penetration, however slight, is sufficient to complete vaginal or anal intercourse.
(B) "Sexual contact" means any touching of an erogenous zone of another, including without limitation the thigh, genitals, buttock, pubic region, or, if the person is a female, a breast, for the purpose of sexually arousing or gratifying either person.
(C) "Sexual activity" means sexual conduct or sexual contact, or both.
§ 2907.04. Unlawful sexual conduct with minor.
(A) No person who is eighteen years of age or older shall engage in sexual conduct with another, who is not the spouse of the offender, when the offender knows the other person is thirteen years of age or older but less than sixteen years of age, or the offender is reckless in that regard.
(B) Whoever violates this section is guilty of unlawful sexual conduct with a minor.
(1) Except as otherwise provided in divisions (B)(2), (3), and (4) of this section, unlawful sexual conduct with a minor is a felony of the fourth degree.
(2) Except as otherwise provided in division (B)(4) of this section, if the offender is less than four years older than the other person, unlawful sexual conduct with a minor is a misdemeanor of the first degree.
(3) Except as otherwise provided in division (B)(4) of this section, if the offender is ten or more years older than the other person, unlawful sexual conduct with a minor is a felony of the third degree.
(4) If the offender previously has been convicted of or pleaded guilty to a violation of section 2907.02, 2907.03, or 2907.04 of the Revised Code or a violation of former section 2907.12 of the Revised Code, unlawful sexual conduct with a minor is a felony of the second degree.
HISTORY: 134 v H 511 (Eff 1-1-74); 143 v H 44 (Eff 7-24-90); 146 v S 2 (Eff 7-1-96); 148 v H 442. Eff 10-17-2000.
IF THEY ARE NOT ENGAGING IN SEXUAL CONDUCT you can still apply for a restraining order and try to have the 18 year old charged with contributing to the delinquency of a minor.
§ 2919.24. Contributing to unruliness or delinquency of a child.
(A) No person, including a parent, guardian, or other custodian of a child, shall do any of the following:
(1) Aid, abet, induce, cause, encourage, or contribute to a child or a ward of the juvenile court becoming an unruly child, as defined in section 2151.022 of the Revised Code, or a delinquent child, as defined in section 2152.02 of the Revised Code;
(2) Act in a way tending to cause a child or a ward of the juvenile court to become an unruly child, as defined in section 2151.022 of the Revised Code, or a delinquent child, as defined in section 2152.02 of the Revised Code;
(3) If the person is the parent, guardian, or custodian of a child who has the duties under Chapters 2152. and 2950. of the Revised Code to register, register a new residence address, and periodically verify a residence address, and, if applicable, to send a notice of intent to reside, and if the child is not emancipated, as defined in section 2919.121 of the Revised Code, fail to ensure that the child complies with those duties under Chapters 2152. and 2950. of the Revised Code.
(B) Whoever violates this section is guilty of contributing to the unruliness or delinquency of a child, a misdemeanor of the first degree. Each day of violation of this section is a separate offense.
HISTORY: 141 v H 349 (Eff 3-6-86); 148 v S 179, § 3 (Eff 1-1-2002); 149 v S 3. Eff 1-1-2002; 150 v S 5, § 1, eff. 7-31-03.
[§ 2151.02.2] § 2151.022. Unruly child defined.
As used in this chapter, "unruly child" includes any of the following:
(A) Any child who does not submit to the reasonable control of the child's parents, teachers, guardian, or custodian, by reason of being wayward or habitually disobedient;
(B) Any child who is an habitual truant from school and who previously has not been adjudicated an unruly child for being an habitual truant;
(C) Any child who behaves in a manner as to injure or endanger the child's own health or morals or the health or morals of others;
(D) Any child who violates a law, other than division (A) of section 2923.211 [2923.21.1] or section 2151.87 of the Revised Code, that is applicable only to a child.
HISTORY: 133 v H 320 (Eff 11-19-69); 146 v H 4 (Eff 11-9-95); 148 v S 181 (Eff 9-4-2000); 148 v S 218 (Eff 3-15-2001); 148 v S 179, § 3. Eff 1-1-2002.
