Incest, which is sexual relations between (non-spouse) family members, is outlawed in most countries, including the United States. Incest laws aim to promote security and unity with the family, and to prevent the genetic problems that often occur in babies whose parents are related.
In the U.S., incest is regulated by state, not federal law, and every state has one or more laws banning this problematic behavior. And while states sometimes vary in defining the outer boundaries of who is considered “family” and the exact behaviors that are off-limits, the underlying goals or policy considerations remain consistent among states.
Recognizing the disruptive nature of incest on healthy family relationships and power dynamics, all state incest laws outlaw sex between close blood relations, and many states also include step-, foster, and adoptive relations, too. And in some states, even unconsummated marriage between close relations is considered incest.
What is “Family?”
For the purposes of incest laws, “family” can mean several things: blood relations, family by adoption or marriage (including step-family members), foster families, and sometimes even “family-like” situations (such as a parent and child who live with the parent’s boy- or girlfriend).
All states include close blood relations— parents, children, aunts, uncles, and grandparents—in the definition of “family.” Closely-related cousins, such as the children of a parent’s sibling, are also included in most states, although more distant cousins are sometimes exempted from incest laws.
In general, the more distant the relation, the less likely that it will be considered as "family" for purposes of incest law. However, other factors (for example, distant cousins being raised in the same household like siblings) can make an otherwise non-problematic relationship incestuous.
Prosecution and Defenses
Often, a situation involving incest also implicates other criminal laws. For example, child abuse and rape (and statutory rape) may be charged as well. Local prosecutors have discretion about whether to bring charges under the state incest law or other applicable laws. Similarly, if a relationship is too attenuated to qualify as an incest crime, the prosecutor will usually have other laws (such as those covering molestation, lewd acts, or rape) under which to prosecute the defendant.
Consent not a defense
A defendant may be convicted of engaging in incest if he knowingly engaged in a sexual encounter with a family member (if no encounter actually took place, the prosecutor may charge the defendant with attempted incest). Because of this, the consent of the other party is not a defense. Of course, as noted, if the victim did not consent and was forced, or was underage, a defendant may face charges for other sex offenses—such as rape and statutory rape—instead of (or in addition to) the incest charge.
Who is charged?
Although the ages of the parties are not relevant in proving that incest took place (and are not a defense to such charges), the age of the parties may be relevant as far as who is prosecuted for the crime. For example, if an adult parent has consensual sex with a minor son or daughter, the parent may be prosecuted, while the child will be considered a victim
But where two siblings of similar age are sexually involved with each other, they might both be prosecuted (although many states handle crimes committed by minors through juvenile or family court). For more on crimes committed by minors, see The Juvenile Justice System.
Old cases and the statute of limitations
All states set time periods in which a crime may be prosecuted, such as five or ten years after the incident. Such laws are intended to ensure that cases are handled relatively quickly, and recognize the danger in prosecuting old cases where the facts may be difficult to discern. In some states, if a long time has passed since the time of an incestuous encounter or relationship and a prosecution, the defendant may claim that the statute of limitations has run.
For more information on state statutes of limitation, with state-by-state information, see Criminal Statutes of Limitations.
Penalties for an incest conviction vary according to state law, but may include separation of family members (if a child is involved, the child may be placed in foster or other care), or a jail or prison term of several months to many years.
For information on felony charges and sentences on a state-by-state basis, see Classification of Crimes: Felonies & Misdemeanors.
Help for Incest Survivors
If you or someone you know is a victim of incest or another sex crime, there is free and confidential help available to you. Contact the Rape, Abuse & Incest National Network (RAINN) for online help and local resources.
Talk to a Lawyer
If you are facing an incest charge, consider consulting with an experienced criminal defense attorney who regularly practices in your area. A lawyer can evaluate the strength of the prosecution’s case against you, help develop any defenses that might apply to your case, and will know how local prosecutors and judges typically handle cases like yours.