We’re all supposed to be born with an innate disgust for incest. It’s been put there by evolution to force us to leave the cave to find a suitable partner for having babies with. But for some people, that part of their brain is apparently broken.

Whether mental illness or a phenomenon known as Genetic Sexual Attraction, here are six couples who committed the ultimate sexual taboo- having sex with, sometimes marrying and even having children with a close relative.

6Bruce and Linda McMahan


In June 2004 Bruce McMahan eloped to England with his 35-year-old daughter. There was no wedding attire or officiant, but the couple exchanged rings at Westminster Abbey and posed for photos.

Adopted at birth, Linda met Bruce for the first time in 1990, subsequently changed her last name to McMahan and began a sexual relationship with him in 1998. From there, Linda and Bruce decided to make their union official, despite the lack of papers, legality or a divorce from their prospective spouses.

But after only a year, which was spent trying to hide their incestuous relationship, Bruce and Linda McMahan fell out after Linda refused to lie for Bruce’s divorce proceedings. Months of legal wranglings followed, with each party using the other for everything from theft and extortion to defamation.

5John and Jenny Deaves


When this Australian couple was famously interviewed by 60 minutes in April 2008, the world took notice. John and Jenny Deaves didn’t have a typical father-daughter relationship after the divorce between John and his daughter’s mother, though Jenny did sporadically spend time with him growing up.

They reconnected in 2000 and both John and Jenny left their spouses to live together as a couple. They’ve had two children together, one dying shortly after birth from a heart defect, and were arrested and charged with incest by an Australian court.

After pleading guilty the Deaves were released by the courts, provided they stop the sexual part of their relationship, which they claimed they curtailed for fear of a prison sentence. The couple has since separated.

4Danielle Heaney and Nick Cameron


Danielle and Nick didn’t grow up as brother and sister. Raised in foster care, Nick Cameron met his half-sister Danielle when she was twenty and he 26.

After three weeks of knowing each other, they began a sexual relationship but were reported to authorities by their mother who walked in on them having sex. Incest in their native Scotland is a felony, and Heaney and Cameron were sentenced to nine months probation where they could not have verbal or physical contact.

They now live together but claim to not be sexually intimate. When they were last interviewed the pair were contemplating a move to France, where incest is not a crime.

3Patrick Stuebing And Susan Karolewski

Patrick Stuebing and Susan Karolewski are vocal activists for changing German laws against incest.
Meeting for the first time as adults, Stuebing (who was adopted at birth) and Karolewski live together as a couple and have had four children together.
All but one child has been taken from them by authorities, and Stuebing has undergone a vasectomy after serving a two-year prison sentence for having sex with his sister. The couple’s lawyer argues that the German laws regarding incest is out of date and should be lifted to allow consenting couple’s privacy.
In 2008, German courts upheld the laws on the basis that inbreeding causes bodily harm to potential children. Stuebing and Karolewski still share a small apartment in Leipzig.

2Mackenzie And John Phillips


Mackenzie Phillips has become the unofficial spokeswoman for consensual incest after she famously admitted to having a years-long affair with her father, John Phillips of The Mamas and the Papas.

Phillips wrote of the relationship, which began when she was still a teenager, in her memoir and told of her father’s desire to elope with Mackenzie to Mexico where they could change identities and raise Mackenzie’s younger siblings as their own children.

Phillips’ younger sisters are torn on the issue, unsure of what to believe and upset that details of their family’s sordid history is up for public discussion. The situation reached an apex recently when sister Chyna Phillips was hospitalized for anxiety relating to the issue.

1Allen And Patricia Muth


A brother-sister couple from Wisconsin, Allen and Patricia Muth met as adults and came to refer to each other as husband and wife. The couple had four children together one of whom was developmentally disabled.

When the Muths left the child in the care of a babysitter longer than they anticipated working months-long hitches as truckers, the child was reported as abandoned and the Muths’ union was brought to light.

Allen and Patricia eventually faced eight and five years of prison time respectively on charges of incest. The case drew parallels to the gay marriage debate.