Why don't we feel sexual attraction toward family members?

I was sitting around the other day and this question popped into my head—it might sound a bit silly, honestly. I was thinking about how I have quite a few attractive cousins in my family, and obviously, there isn't even a flicker of attraction there, which got me wondering... what is it that actually stops us from seeing relatives in that way? Is there some sort of built-in mechanism in our brains that just shuts down any kind of sexual thought when we look at a family member? Like, why is it fundamentally impossible for me to imagine being with a cousin?

I hope you guys get where I'm coming from, I really don't mean anything bad by asking! 🙂

First off, we’re talking massive social conditioning here.
It’s easily one of the biggest taboos in human society.

I mean, it's not like nobody has ever had the thought, but we've been totally programmed to view it as wrong and twisted—to make sure we don't even look at it that way.

There’s actually a theory out there suggesting that part of why humans and primates feel this drive to form tight-knit packs is to minimize incestuous relationships.

I remember reading about some studies done on chimpanzees and rhesus macaques where they concluded that mother-offspring incidents are way more common than sibling ones. Or maybe it was something else... I can't quite recall if it also depended on the specific age group involved.

Anyway, they didn't really manage to prove it's a biological trigger. It seems to be mostly down to social conditioning.

I mean, obviously there’s some kind of attraction happening if incest is even on the table.🤷

Personally, as someone who considers themselves pretty mentally sound, I just can't wrap my head around the idea of sexual relations within a family.🙂
And as for chimpanzees... well, I guess we aren't really at the level of chimps or other animals, are we?🤷

Look, family members pull you in on a totally different level. It's not about sex—it's deeper than that. I'd give just about anything else for a family member, but I can't just swap out

steelcrane5 said:I was sitting around the other day and this question popped into my head—it might sound a bit silly, honestly. I was thinking about how I have quite a few attractive cousins in my family, and obviously, there isn't even a flicker of attraction there, which got me wondering... what is it that actually stops us from seeing relatives in that way? Is there some sort of built-in mechanism in our brains that just shuts down any kind of sexual thought when we look at a family member? Like, why is it fundamentally impossible for me to imagine being with a cousin?

I hope you guys get where I'm coming from, I really don't mean anything bad by asking! 🙂

The reality is that family members can actually be sexually attractive during childhood—either because they are physically appealing or because you're in that formative, semi-developed stage of development. They are essentially the first people your brain learns to model interpersonal relationships upon. However, with a relatively healthy psychosexual development, you either overcome that attraction, let it fade away, or sublimate it into something more constructive... so when actual sexual experiences begin, it ceases to matter.

Of course, for some people, this isn't resolved—or at least not in time—which is why incest exists.
Then again, incest can also stem from pure convenience, economic necessity, and so on...

As for finding an attractive cousin interesting—even if you aren't close to them—that's actually quite normal. If it happens, you just handle it the same way you would if you developed a crush on a friend's partner: you acknowledge it, and then you move on as if nothing happened...

gentlesailor25 said:I mean, obviously there’s some kind of attraction happening if incest is even on the table.🤷

Personally, as someone who considers themselves pretty mentally sound, I just can't wrap my head around the idea of sexual relations within a family.🙂
And as for chimpanzees... well, I guess we aren't really at the level of chimps or other animals, are we?🤷

It’s really about our advanced social and cultural setups. Biologically speaking, the gap is tiny—almost nothing.

Look, cats don't mate with other cats—that's just straight-up twisted and wrong.

Maybe cats are just socially conditioned too? 🤷 I wouldn't bet my life on it... someone "healthy" might still be lured in by a family member if they weren't aware of the blood connection.

Kenneth Garcia9 said:Maybe cats are just socially conditioned too? 🤷 I wouldn't bet my life on it... someone "healthy" might still be lured in by a family member if they weren't aware of the blood connection.

Honestly, that happens all the time. People fall in love and then find out they're actually related.
In this case, it's more about the attraction that happens when people live under the same roof.

Even in animal packs, there’s social conditioning at play—just on a lower level.
There isn't a proven biological trigger for it, so most experts assume it's just pure social conditioning.

dustyranger64 said:Honestly, that happens all the time. People fall in love and then find out they're actually related.
In this case, it's more about the attraction that happens when people live under the same roof.

Even in animal packs, there’s social conditioning at play—just on a lower level.
There isn't a proven biological trigger for it, so most experts assume it's just pure social conditioning.

I agree. It suggests biology isn't really the main driver here... it's more about social norms.

Kenneth Garcia9 said:Maybe cats are just socially conditioned too? 🤷 I wouldn't bet my life on it... someone "healthy" might still be lured in by a family member if they weren't aware of the blood connection.

I’m with you on that. There’s actually this concept called "genetic attraction." It’s that weird pull you feel when you run into a long-lost relative. It even applies to parent-child dynamics.

The thing is, you don't perceive them as a relative; you see them as a potential partner, and the attraction is amplified because your genetic material is so compatible.

It works the exact opposite way with childhood friends. If you've known someone since you were kids, you end up seeing them more like a brother or sister. Even if you can clearly tell the difference between an actual blood relative and a friend, that feeling remains. And that goes for real siblings, too.

For example, my brother listed one of his first-grade buddies as a sibling on Facebook. Since I grew up with my twin brother and we spent every single summer vacation together until we were eleven, the idea of anything romantic happening between us is just revolting.

dustyranger64 said:It’s really about our advanced social and cultural setups. Biologically speaking, the gap is tiny—almost nothing.

I recall seeing data suggesting we share roughly 98% of our genetic makeup with bonobos—maybe even more.

Genetically speaking, our closest relatives are gorillas, chimpanzees, and bonobos. It’s actually quite a startling fact that even a fruit fly shares roughly 60% of its DNA with us, depending on which specific calculation method you use. What does that imply about the remaining 40%—that massive gap in our genetic makeup? Does it suggest something deeper about what truly separates us from the rest of the biological world?

I recall reading somewhere that > noted how most genetic disorders are passed down through recessive lines, and naturally, incest significantly spikes the likelihood of those traits manifesting in the phenotype. Evolutionary pressures essentially work in direct opposition to the impulse toward incest, which is precisely why humans, as a species, generally tend to avoid it. Is it not simply nature's own way of safeguarding our survival?

steelcrane5 said:I was sitting around the other day and this question popped into my head—it might sound a bit silly, honestly. I was thinking about how I have quite a few attractive cousins in my family, and obviously, there isn't even a flicker of attraction there, which got me wondering... what is it that actually stops us from seeing relatives in that way? Is there some sort of built-in mechanism in our brains that just shuts down any kind of sexual thought when we look at a family member? Like, why is it fundamentally impossible for me to imagine being with a cousin?

I hope you guys get where I'm coming from, I really don't mean anything bad by asking! 🙂

Maybe humans are just naturally drawn to whatever is different. Maybe we gravitate toward things that feel mystical, new, or like that missing piece of the puzzle... who knows, I guess.

When people talk about incest, they usually mean both blood relatives and adopted ones too...

I've heard stories about how Eskimos used to offer their wives to strangers as part of certain customs, and I think I read somewhere that "sacred prostitution" in ancient societies was actually a way to introduce new genetic elements to a population...

Even Paulo Coelho wrote about the taboo idea of a man feeling turned on while his wife is with another man in one of his books...

And I mean, even cats—during mating season, they just wander around, right? If I remember correctly, they end up having kittens with whoever happens to be hanging around.

Maybe, when it comes to how humans pick partners over time, the main driver is just this deep urge for change. I don't necessarily mean polyamory or anything like that, but maybe it's just more natural to be attracted to difference rather than similarity... 🤷

Carl Castillo69 said:Look, cats don't mate with other cats—that's just straight-up twisted and wrong.

that just isn't true...

Look, I get it. There’s always that pull toward certain cousins you haven't seen in years or whatever. But honestly? You just have to get that out of your system...

I don't buy this whole idea that we have some built-in biological "off switch" for attraction to relatives. Honestly? It feels more like society just spends years drilling the concept of family into your head—basically conditioning you to view certain people through a lens where anything sexual is totally off the table. That’s the real barrier. Of course, it's a different story if you suddenly find out the person you're vibing with actually turns out to be your uncle, cousin, or sibling.
Just look at how they handled that whole forbidden love mess in 😁

So, I've got this gorgeous cousin... honestly? I wouldn't dream of sleeping with her—but man, would I love to catch a glimpse of her without any clothes on!

Jeremy Alvarez5 said:Maybe humans are just naturally drawn to whatever is different. Maybe we gravitate toward things that feel mystical, new, or like that missing piece of the puzzle... who knows, I guess.

When people talk about incest, they usually mean both blood relatives and adopted ones too...

I've heard stories about how Eskimos used to offer their wives to strangers as part of certain customs, and I think I read somewhere that "sacred prostitution" in ancient societies was actually a way to introduce new genetic elements to a population...

Even Paulo Coelho wrote about the taboo idea of a man feeling turned on while his wife is with another man in one of his books...

And I mean, even cats—during mating season, they just wander around, right? If I remember correctly, they end up having kittens with whoever happens to be hanging around.

Maybe, when it comes to how humans pick partners over time, the main driver is just this deep urge for change. I don't necessarily mean polyamory or anything like that, but maybe it's just more natural to be attracted to difference rather than similarity... 🤷

Look, this isn't about some intellectual curiosity for novelty. It's about scent—specifically the kind women sense. And I don't mean a literal "scent" like a perfume you can describe or pin down; it's more like that scentless, inexplicable pull where someone becomes suddenly, inexplicably attractive to you...
Meanwhile, blood relatives—people who are genetically similar—basically radiate an aversion to sexual activity (in terms of half-breeding) through pheromones. They essentially "smell" wrong to us...
So, if you strip away every other personality trait, the most attractive people would be those with genetic profiles as different from ours as possible. If we stick to this animalistic logic, it's like when a gorgeous, fluffy poodle gets bred with another poodle that looks exactly like her, but then she ends up ignoring him entirely to fall head-over-heels for the ugliest dachshund in the park...

As for men, I'm convinced it's mostly down to social conditioning...

crimsoncanyon2 said:Look, this isn't about some intellectual curiosity for novelty. It's about scent—specifically the kind women sense. And I don't mean a literal "scent" like a perfume you can describe or pin down; it's more like that scentless, inexplicable pull where someone becomes suddenly, inexplicably attractive to you...
Meanwhile, blood relatives—people who are genetically similar—basically radiate an aversion to sexual activity (in terms of half-breeding) through pheromones. They essentially "smell" wrong to us...
So, if you strip away every other personality trait, the most attractive people would be those with genetic profiles as different from ours as possible. If we stick to this animalistic logic, it's like when a gorgeous, fluffy poodle gets bred with another poodle that looks exactly like her, but then she ends up ignoring him entirely to fall head-over-heels for the ugliest dachshund in the park...

As for men, I'm convinced it's mostly down to social conditioning...

To be perfectly honest, I’m at a bit of a loss here. What exactly is a "scentless scent"? Is that just an oxymoron? Are you suggesting we simply don't perceive it on a conscious level? Furthermore, I'm genuinely unsure if there is actually such a stark difference between how pheromones influence mate selection in men versus women, or if such a gap even exists to that degree. For my part, I suspect that men also rely on pheromonal cues when choosing a partner—alongside a massive array of other signals, of course—though I certainly don't believe pheromones act as the sole deciding factor. And what, precisely, is the role of pheromones in the biological mechanism for avoiding inbreeding? Do they play any actual part in that specific aspect of partner selection?