How common is sibling attraction? (+9 scary facts)

In this article, we answer some common questions about intimate relationships with family members. How common is sibling attraction? Are sisters attracted to their brothers? Why am I sexually attracted to my brother?

Can a brother fall in love with his sister? What happens when siblings mate? Are intimate relationships with family members a crime in the UK?

What about other countries? Keep reading to find the answers to all of these questions, and even more – the reasons behind sibling relationships. 

How common is sibling attraction? 

If you investigate the subject beyond the surface, you find that these relationships are more widespread than you think and, in many cases, not only consensual but also motivated by the same things as conventional adult relationships: love, need, desire, loneliness and attraction. 

This raises many ethical questions about consent, victimization, legality and morality, but also a very important one: can someone have a healthy, consensual relationship, both sexual and emotional, with a close relative?

It is difficult to persuade psychologists to officially talk about this topic outside the abusive context because they fear that it would legitimize it and that would undermine the victims of cases of non-consensual relationships with other family members. 

But the general opinion is that one of the important factors of consensual intimate family relationships seems to be both the fractured nature of modern families and their closeness to other families.

How Common is Sibling Incest?

Sibling incest is not very common, even though it is assumed to be very common. There is a lot of representation of sibling incest in mainstream pornography, but in real life, this sort of relationship is not very common, because of various genetic reasons. Sibling incest used to be even more uncommon but because of how common it has become in mainstream media.

How Common is Brother Sister Incest?

Brother sister incest is not as common as it is portrayed to be in media or in pornography. Father daughter incest, which is about 34.9%, has been seen as being one of the most common types of incest, after which the other type of incest, which is brother sister, is at 14%.

Are sisters attracted to their brothers?

There are enough cases of romantic and passionate love between brother and sister to convince us that yes, it can happen.

The first and most important thing is to try to understand the nature of your feelings and why brotherly love seems to have turned into romantic, passionate love.

If you feel that you have fallen in love with your brother or sister, it is very possible to try to deny your feelings, to ignore them, to try to find other explanations than that you really love your brother or sister in a way that is socially unacceptable.

It is important to know that denying what you feel does not help you most of the time – it can even hurt you. 

Although it seems an impossible, unnatural situation, it sometimes happens.

Therefore, it is important to know, analyze and understand your feelings, to try to find out how a brotherly love becomes more.

Love and physical attraction between brother and sister can be a form of co-dependence.

If you feel that you have fallen in love with your brother or sister, it may be the strong, deep feelings of co-dependence.

When two brothers go through many things together, usually through difficult situations and stay close to each other, protecting and comforting each other, they may begin to feel dependent on each other, needing to be with each other to feel safe.

When the brother or sister is the only person who has offered love, closeness, security, protection and support, there is this need to be with him / her, to always rely on him / her.

Addiction that is extremely similar to passionate love, in which you feel that you need the other more than anything else.

The older brother or sister often feels a deep protective love, taking care of the youngest, while the latter learns to depend on the former.

A deep co-dependence is created, and the siblings may feel that they cannot bear to live separately, to live with other people (in this situation a psychologist can help: no type of co-dependence relationship is healthy!) .

All this shows that love between brother and sister can take various forms for various reasons; of course, often love is felt only by one of the brothers, the other unaware of the existing feelings.

Many people say either that a romantic, passionate, physical love between brothers and sisters is impossible, or that it is about unnatural exceptions. 

And yet, it happens: and the simplest argument to prove that yes, there may be such a kind of love between brother and sister lies in the very taboo of intimate family relationships!

If naturally there was no physical attraction between first-degree relatives, then why, since ancient times, human societies have felt the requirement to strictly impose the taboo of intimate family relationships, to clearly regulate the rules, to impose severe punishment? 

Because this attraction may exist – but given the fact that it is neither socially nor biologically desirable (children from such unions are at extremely high risk of genetic defects) this taboo was created and imposed in all human societies, this prohibition of intimate family relationships (of course, in some cultures this taboo referred only to parents and children, brothers being allowed to be together).

Why am I sexually attracted to my brother?

In psychology and psychiatry, it is often discussed about an extension of the famous Oedipus complex; more precisely, romantic love and sexual attraction do not go to the opposite-sex parent, but to the opposite-sex brother.

This generally happens when the brother of the opposite sex has largely taken over the role of the parent, raising, protecting and loving his younger brother/sister. 

Therefore, the person sees in the figure of his brother/sister in fact a reflection of the paternal/maternal figure.

If you feel that you have fallen in love with your brother/sister, it may be this brother or sister complex.

Think about what your brother or sister meant to you, what made you close and unique, what you find and love in his person. 

Many times, if it is about this psychological complex, your love becomes rather an obsession: you can only think about him/her, you do not feel attraction towards anyone, apart from him/her, you just want to be with him/her. 

You also become extremely jealous, wishing all the attention and love of your brother or sister.

When feelings are obsessive, you can find support and understanding by calling a psychologist (no obsession is healthy, especially if we are talking about this complex of brother or sister).

Can a brother fall in love with his sister?

Psychologists talk about multiple cases in which a brother and a sister who grew up separated in childhood meet again and fall in love with each other.

If you are in this situation (you did not grow up with your brother/sister) and you feel that you have fallen in love with him, it can help you better understand why this is happening.

It is perfectly explainable why a person can fall in love with his or her brother or sister once he/she sees him/her again after a long separation.

It’s about what you recognize in that person – you recognize parts of yourself and your parents, you recognize aspects that are so familiar and yet new. 

Every person is attracted to certain traits similar to his own (and siblings have similar traits, even similar levels of intelligence, even similar interests and abilities), but also traits that seem familiar (these are traits that the person remembers to loved ones in childhood: parents, grandparents, other significant adults in the life of the young child). 

Therefore, this similarity and familiarity suddenly found in a person gives birth to an intense attraction, an attraction that takes the form of romantic or passionate love, even if normally a brother and a sister would not have such a connection.

Why does it happen most often that someone falls in love with his brother or sister after they have been separated for a long time?

Simple: when a brother and a sister grow up together, share the same house and sometimes even the same room, there is a so-called “desensitization” of the attraction.

It is an effect that is believed to be naturally programmed to prevent intimate family relationships. 

The constant closeness leads to saturation of stimuli and too much familiarity between brother and sister, which kills any attraction.

This can be seen even in people who are not relatives, but who grow up in the same house: for example, children who are raised together, once adults, do not feel attracted to each other, looking for more distant partners.

They have simply become too familiar, too close, so they feel brotherly love and not a romantic and physical one.

On the other hand, if two children grow up separately, once they see each other again, they can feel that deep connection given by genetics and can interpret it as romantic love (there is the feeling that you have found your soulmate because a brother or a sister does not only share common traits but also share something of your being, genetic material and maybe spirit). 

There is a certain familiarity, but there is no saturation of stimuli – on the contrary, this familiarity is paradoxically perceived as new and exciting. 

Brother and sister are instinctively attracted to each other and because there is no saturation of stimuli to kill any trace of physical attraction, they will fall in love with each other romantically and passionately (there is that unique connection that exists between any brother and sister, but is doubled by attraction). 

The relationship is new, the deep connection between them is old, from their birth.

What happens when siblings mate?

When siblings mate, meaning having sexual relationships, perhaps the biggest consequence could be the birth of a child.

From co-consanguinity (n.r.- sexual intercourse between people with the same blood) there are born children with numerous genetic diseases. 

The resulting children may have malformations, retardation, Down syndrome, depending on the recessive genes.

They can appear from visible organic malformations to some detectable only through investigations.

Intimate family relationships is mostly accepted in the adult industry, where it is the most consumed type of adult-content. However, these relationships – even consensual ones – can have dire long-term consequences.

That is why there is little chance that this will ever be accepted as normal or a comfortable topic of discussion.

Are intimate family relationships a crime in the UK?

Yes, according to the Sexual Offences Act 1956, Intimate family relationships are a crime in the UK.


It is an offence for a man to have sexual intercourse with a woman whom he knows to be his grand-daughter, daughter, sister or mother.


In the foregoing subsection ” sister ” includes half-sister, and for the purposes of that subsection, any expression importing a relationship between two people shall be taken to apply notwithstanding that the relationship is not traced through lawful wedlock.


It is an offence for a woman of the age of sixteen or over to permit a man whom she knows to be her grandfather, father, brother or son to have sexual intercourse with her by her consent.


In the foregoing subsection ” brother” includes half-brother, and for the purposes of that subsection, any expression importing a relationship between two people shall be taken to apply notwithstanding that the relationship is not traced through lawful wedlock.

Speaking of other countries, however, intimate family relationships between parent and child is universally seen as abuse, due to the unequal power dynamics between parent and child that does not allow for informed consent. But the dynamic between the brothers revolves in more turbulent waters, from a legal and ethical point of view.

For example, in the case of an intimate family relationship that resulted in four children, the German Ethics Council concluded in 2014 that “the right of adult siblings to make decisions in a consensual relationship weighs more heavily than the abstract good of the family.”

Although no data on consensual intimate relationships has been collected anywhere in the world, the statistics are quite surprising. In the United States, in the 1990s, it was estimated that between one hundred thousand and one million cases of intimate family relationships occurred annually. 

The scale of global intimate family relationships varies depending on the numbers you look at – generally due to the very private nature of the phenomenon that prevents accurate data collection – but it is believed that between ten and twenty per cent of the population have intimate family relationships. In Brazil, the rate ranges from 0.05 to 21 per cent.

How common is it for brothers and sisters to experiment?

It is actually quite common for brothers and sisters to experiment, but this experimentation tends to happen before they reach puberty in most cases, and it usually does not go farther than the brother and sister trying to understand sexuality through exploration with each other.

Furthermore, brothers and sisters experimenting is more common with cousins rather than with real brother and sister, because of a hypothesis known as the Westermarck impact, which states that people who live together through the formative years may become desensitized to each other in terms of sexual attraction.

However, even though this hypothesis tends to say that people who live together are unlikely to experiment, it does not mean that brothers and sisters don’t experiment at all, in fact it is just that these relationships are quite quite hidden, or at least they used to be, before the prevalence of adult-content that is centered around the concept of intimate family relationships.

There has been a rather steep rise in videos about taboo relationships between step sisters or step brothers and experimentation between brothers and sisters or even step fathers and step daughters.

Sexual attraction between people who are related is usually uncommon, but that does not mean that it is uncommon for brothers and sisters to experiment, but it may be possible that it is more common among kin members who are separated at birth, and they may feel sexual attraction towards each other more so than those that have lived together since they were young.

This may be because it is hard for brother and sister to experiment that much given that they have always lived close to each other, and therefore they don’t have the kind of relationship that other brothers and sisters who live away.

Additionally, sometimes brothers and sisters experiment due to them meeting only once in a while, or in cases where the parent is not the same, that is, step brothers and sisters, which is also considered legal in many places, and states in the United States.

A study done in New England indicated that generally 10% of guys and 15% of females had been involved in or experienced some type of sexual contact with a sibling or sister, and the most well-documented instance in this behavior was usually stroking of genitalia.

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Why would a brother be attracted to his sister?

A brother might be attracted to his sister because of the simple reason that he is curious about the opposite sex and therefore it is causing him to look towards a source that is familiar and comfortable from which he can learn about it.

Many times, the most basic reason for the brother being attracted to his sister is very simply that he is hormonal, and perhaps he is suffering from some social anxiety, which leads to him looking at his sister in a sexual way, though he ordinarily wouldn’t.

In some cases, a brother might also be attracted to his sister because he is hormonal or approaching puberty and he has mistaken a general curiosity and need for sexual release as attraction, which is something that happens even in adults, so it can definitely happen in adolescents.

Another possible reason why a brother might be attracted to his sister may be that they have not lived together all their lives, and that makes it easy for them to see each other as virtual strangers rather than people who are related in some way.

Physical relationship with sister

An individual might have a physical relationship with their sister as a means of experimentation or understanding sexuality, and these relationships tend to begin around the ages of 9 to 16 because this is the time when they start to discover their sexual organs and sexual feelings.

A physical relationship with one’s sister is a type of intimate family behavior that may also develop between a brother and a sister after they hit puberty, and this is more common in brothers and sisters who live far away, or are somehow less emotionally attached to one another.

In some cases, a physical relationship between sister and brother or even just two sisters may also come about as a game, and then continue because it seems fun, or it might also continue because the thrill of doing something that is wrong may add to the game, causing it to go on longer than it would otherwise.

It may also continue due to the strict regulations on dating or mingling with the members of the opposite sex in general, by parents or family or just society as a whole, and since that doesn’t limit the hormones that one is experiencing, a playful activity between siblings may turn into a physical relationship with a sister.

Why am I attracted to my older sister?

You may be attracted to your older sister because you are hormonal and perhaps you are not able to reach out to members of the sex you are attracted to outside of the family, because of social anxiety or other factors, like not being able to leave.

There are some other reasons why you might be attracted to your older sister, some of which include:

  • Sex might be too taboo around the household, making the desire or need that much more pronounced, projecting it on to people nearby
  • You might not be experiencing as adequate a release as you and your body need, by way of masturbation or indulging in other sexual fantasies
  • You might be experiencing a particularly turbulent and hormonal puberty
  • There may not be as much age difference between you and your older sister, as this also contributes in the sister may be seen more as a peer and less as a blood relative
  • You may have gotten too influenced by adult-contents or mainstream media that depicts such relationships often and you might have seen too many instances of a brother being attracted to their older sister being normalized.

Whatever the reason for you being attracted to your older sister, it is not something that is totally normal, and you need to talk to somebody about it, especially if it is causing you significant distress.

GSA Half Siblings

GSA between half siblings stands for Genetic Sexual Attraction between half siblings, that is, a genetic sexual attraction between people who have either a mother or father in common, but not both.

GSA is a description of a rather powerful sexual attraction that occurs when biological relatives like half siblings, or even parent and child, or siblings meet for the first time as adults and expereince attraction towards each other despite sharing genetic material.

GSA between half siblings, siblings, parents and children or even cousins, is a concept that has been around since the 1980s when it was first identified by Barbara Gonyo, who fell madly in love with her son.

Genetic sexual attraction happens when estranged people who share blood relations meet for the first time in their adulthood, which means that they basically meet as strangers who might not even be related.

The evolutionary perspective behind GSA in half siblings, siblings or cousins may simply be that nature tries to propel forward the process of procreation, due to which the genetic and biological ties are immediately turned into potential factors for successful progeny.

There have been many instances of GSA between half siblings and real siblings as well, like in this case, where a woman met her long lost brother after 36 years and immediately became attracted to him:

We just looked at each other and it was like instantaneous, the attraction, It’s not even about the sex. It’s a bond unlike anything. Nobody can understand this bond it’s so strong.”

They had dinner after the initial meeting, and after that they had consensual sex, about which she says:

“I freaked out. I was like, ‘What is wrong with you?!’ We were both like, ‘What have we just done? Joe wasn’t comfortable with people knowing about it.”

Why Am I Attracted to Family Members?

You might be attracted to family members because you have not been able to get adequate release with people or because you have experienced dysfunctional family ties which have led to a blurring of familial boundaries, leading to a sexualization of family members.

We are usually not attracted to family members because we have always lived with them and this desensitizes us to them sexually, and leads to not feeling attraction towards them.

However, there are some cases in which one might be attracted to their family members, one instance may be when they have not always lived with their family members, and therefore they are meeting for the first time after reaching puberty so they see each other as practically strangers.

Another instance, which most people may consider much more problematic for various reasons, is when there is a psychological distance between the family members, which may not be as significant as a physical or geographical distance in real life, but it may be just as potent in leading to attraction between family members.

When there is no connection between the family members, the possibility of attraction between them becomes much higher, and while it may seem odd that distant members in a family may be attracted to each other, it is possible when there is no hostility, just distance.

Attraction Between Cousins

Attraction between cousins is far more common than attraction between siblings or even step siblings, and this may be because they live far away from each other and don’t meet as regularly, and are therefore not as desensitized to each other as they are to their siblings or other family members.

It is also possible that there is more attraction between siblings because while there is a sense of taboo attached to this attraction, there isn’t as much social stigma, which is evident in the fact that cousin marriage is legal and allowed in many states in the United States.

In fact, attraction between cousins does often culminate into marriage or serious relationships as well, which shows in the fact that these states allow marriage between cousins:

  • Alabama
  • Hawaii
  • Maryland
  • Massachusetts
  • New Jersey
  • New Mexico
  • New York
  • Rhode Island
  • South Carolina
  • Alaska
  • California
  • Colorado 
  • Connecticut
  • District of Columbia
  • Florida
  • Georgia
  • Tennessee
  • Vermont
  • Virginia

These laws exist to ensure that people are not just fooling around and there are more serious laws that the person needs to adhere to in many states before they can marry a cousin they are attracted to, most of which involve needing one of the cousins to be infertile or older than 50, 55.

Long-lost siblings fall in love

Long lost siblings often fall in love, and the reason for this is the Westermarck impact, which you may remember refers to people who share genetic material meeting and falling in love when they meet for the first time.

The reason behind this is possibly that people who don’t live together all their lives tend to have no reason to think of each other as a blood relative, which takes away a great deal of taboo that is usually attached to intimate family relationships.

Many rich and famous families in the past have dealt with intimate family relationships as a means of keeping bloodlines pure, but it started becoming a thing that was taboo and not allowed when it became clear that children of individuals who are related can have major problems.

There have been many instances of long lost siblings falling in love, look at these two stories, for instance:

“From the moment we met, I was smitten, and continued to be drawn to her like a magnet. As I got to know her, I felt she had given me a life transmission. She put a smile in my heart and a spring in my step.”

“Although Joe and I are siblings, when we met, we both fell madly in love with each other.

I know we share the same blood, but we never grew up together so it is completely different to other siblings.

I was adopted when I was three, I always felt something was missing and yearned to find my real family.”


In this article, we answered some common questions about intimate family relationships How common is sibling attraction? Are sisters attracted to their brothers?

Why am I sexually attracted to my brother? Can a brother fall in love with his sister?

What happens when siblings mate? Are intimate family relationships a crime in the UK? What about other countries? 

Even more, we described the possible reasons behind sibling relationships. 

As a summary, there are enough cases of romantic and passionate love between brother and sister to convince us that yes, intimate sibling relationships can happen.

The first and most important thing is to try to understand the nature of your feelings and why brotherly love seems to have turned into romantic, passionate love.

If you have questions or comments on the content, please let us know!

FAQ on How common is sibling attraction

Are sisters attracted to their brothers?

There are cases when sisters feel attracted to their brothers, however, this is not common!

Sometimes, when siblings grow apart, they later meet and fall in love.

The reason behind this is the familiarity of their traits, that makes them believe they have found the ideal partner. 

Is it normal to be attracted to family members?

It is not normal to be attracted to family members, however there are enough cases out there to prove that this happens.

There is even a term for this, called Genetic Sexual Attraction, or GSA. 

Why don’t we find our siblings attractive?

We do not find our siblings attractive because we grew up too close to them.

The constant closeness leads to saturation of stimuli and too much familiarity between brother and sister, which kills any attraction.

This can be seen even in people who are not relatives, but who grow up in the same house.

What is it called when you are attracted to your sibling?

When you are attracted to your sibling, you may speak of Genetic sexual attraction.

GSA means that a strong sexual attraction may develop between close blood relatives, but only when the two first meet as adults.

Is it illegal to sleep with your cousin?

In most countries, yes it is illegal to sleep with your cousin, parent, grandparent, sibling. 

What is it called when a daughter is attracted to her father?

When a daughter between the age of 3 and 6 is attracted to her father we may speak of the Electra complex. 

What we recommend for Relationship & LGBTQ issues

Relationship counselling

  • If you are having relationship issues or maybe you are in an abusive relationship then relationship counselling could be your first point of call. Relationship counselling could be undertaken by just you, it does not require more than one person.

LGBTQ issues

If you are dealing with LGBTQ issues then LGBTQ counselling may be a great option for you. Maybe you are confused as to your role and identity or simply need someone to speak to. LGBTQ counsellors are specially trained to assist you in this regard.


DeYoung, M., & Lowry, J. A. (1992). Traumatic bonding: Child Welfare: Journal of Policy, Practice, and Program, 71(2), 165–175.

Pendergrast, M. (1995). Victims of memory: accusations and shattered lives. 

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