What are the odds that someone looks like you

I don’t know how to describe the math of this (I don’t know a lot of math) but what are the odds that a person will resemble you 80%, or 90% or 99% in appearance?

Certain things like sex eliminate half the population. Then you have race and ethnicity which eliminate a lot of people. Plus hair color, eye color, height, weight, build, etc.

How much genetic diversity is their in our appearance in the sense of how many people would you have to be around before you found one who resembled you with 90% certainty (no idea how to define 90%) or 99% or 80%? A million, 100 million a hundred thousand?

Is there a relatively finite number of possible appearances (not including things like hair color or hair style, just considering genetically determined appearances) people generally have before it becomes difficult to tell the difference between people?

Good question-I’ll just link to an older thread on doppelgangers.

I’m a big guy with a beard. There’s millions of us. Apparently we all look alike.

I look very much like my male-line great grandfather. You could mistake a picture of him for a picture of me if you ignore the context of the photo.

How can you quantify resemblance? It is subjective.

I look so much like Stephen King, I get mistaken for him in public.

My favorite was when one guy asked me if I was Stephen King, and his buddy asked him who Stephen King was. He answered, “He writes those scary-ass books.”

So, in my case, probability 1.0

Facial recognition software will soon make it easy to find our doppelgangers on the internet. Google already searches for a matching image. It’s useful for finding copyright violations. Or a higher res version of a photo you already have.

Won’t be long and I bet you could upload your head shot and search for similar faces.

No not really, it is math. Facial similarity in particular depends on math just like human pattern recognition does and that is why face recognition programs work reasonably well even today. The field is still in its adolescence at best and probably in its infancy but you can quantify it.

Once you add in hair, body shape, height, facial expressions, and everything else that makes up an individual, the chance of an exact or close match goes down but it still happens to make a very close match sometimes.

Have you ever wondered how a simple drawing by an artist sketched in very few strokes is identifiable as a given person even if the feature are grossly distorted? You see them all the time in political cartoons and elsewhere and they still work because the proportions of the face are retained even if the absolute values are not. That happens by chance with different people as well.

I don’t know how to answer the question in the OP exactly. Some of it depends on the person in question that you want to match. Saddam Hussein didn’t find it difficult to find some near exact duplicates of himself to serve as body doubles but it us probably much easier when you are say a Middle Eastern male of typical build with facial hair than say 6 foot tall blonde, haired blue-eyed female.

You really need a database of a large sample of people combined with advanced recognition software to answer this question. I am sure it is being studied somewhere but I don’t know what the false positive rates are in comparing different people across the entire population. It is non-zero though based on some well-known examples.

Everything resembles everything else in an uncountable number of ways. You can only start making comparisons once you have made the choice as to which aspects or dimensions of resemblance are significant to you, and that is a subjective choice. (It is only possible for a computer to make such comparisons because someone, the programmer, has made those choices for it.)

There probably aren’t many people who look like me here in Ontario, but I understand that in Southeast England, there are lots.

I have been mistaken for two different actors that have no resemblance to each other. Ed Harris and Ernest Borgnine. I am probably built more like Harris and carry myself similar but Borgnine and I have a similar facial structure including the gap in the front teeth.

It’s difficult to quantify, but if you get told often that you look like someone else, you probably resemble that person more than the average person does. But when talking about a doppelganger it should be someone who looks a lot like someone else, not merely a resemblance. They don’t have to be identical twins, but close enough that the vast majority of people would say they look very similar.

I would guess near 100%. Hell, in my own high school, I had a doppelganger. He was a senior when I was a freshman. I was really confused when, during my first week of school, I was walking through the senior hallway and all these seniors buddied up to me like they knew me. “What a friendly school,” I thought. I only realized a bit later that they had me confused with my lookalike, with whom they went to school with for three years at that point. I have to admit, the resemblance was uncanny.

are you looking for a line-chart style graph-stat? as in “a 60% chance someone looks 78% identical, 34% chance someone looking 87% identical,” and so on and so forth?

math and i have a restraining order situation going on, so i can’t even get within 500yards of the actual calculations…but i would presume it would be impossible to quantify in figures.

i would also guess the odds diminish at an exponential rate the closer to “identical” you want to get.

i have found a lot of people online through various photo sources who look marginally like me. i have saved a few jpgs, come across them later, and wondered why i looked so weird that day. “oh wait. that’s not even actually me.” derp.

anecdotal hijack:

i worked with a guy in HS who was strong evidence against Darwinism. he was so stupid…the mere fact he stayed alive was an affront to the concept of “ambivalent universe.”
i decided to exploit his lack of intelligence by playing pranks all the time. the best one was the time i convinced him i wasn’t me, but was a guy who just looked like me.

the ruse was that real me had a date, so *fake me *was enlisted to cover my shift, thus allowing real me to go on the date. of course he called immediate bullshit, so i said “yeah it’s stupid. but please don’t tell anyone, even if it’s not true.”

then i pretended i had no idea how to do the most menial duties every time he was nearby. i would ask people for help doing very common things “i” should know. i mixed feigning jobplace ignorance with a hearty dosage of “oh yeah i knew that! duh.” after seeing me fake-struggle all night, he finally bit the hook. it wasn’t long before he was noticing “differences in how fake me looks vs real me.”

he noticed fake me was shorter and not as stocky. and that my hair was different. of course none of that was true, he just manifested traits to suit what his brain decided was true.

next time “real me” was at work with him, he kept making allusions to our “inside joke” and shared secret.

/hijack off.

It can’t be all that uncommon to have ‘acceptable’ level look alikes. I mean, you can hire impersonators for just about every celebrity to come to your event.

I can’t answer the OP directly, but it might be worth looking at studies of lineups in police work. I know that false positives are pretty common even when the police are working hard to avoid cuing the witness. This would give you at least some baseline statistics for how easy it is to mistake one person for another.

There’s a difference between someone you KNOW, and someone you only saw once for a few minutes or so.
The other thing is, cartoon caricatures don’t work by “preserving the proportions”. They work by exagerrating them. Prince Charles or Obama has big ears - make them bigger. Jimmy Carter has big teeth - make them bigger. GWB has squinty eyes - make them squintier. Why? Because these are the characteristics that set a person apart, make them distiguishable. We start with the basic shape, and then consider each feature in its refinement. OTOH, a caricature is not intended to actually doppelgang(??) the original. Rather, it pokes fun at them.

I had identical twin relatives. I sw them maybe once o twice a year for a few days. I could not tell them apart unless I looked for cues - slightly different hair, what they wore that day - and remembered them. their parents had no problem.

So I would suggest a series of sliding scales - able to fool a police lineup (oh, great), able to fool random not-close co-workers, able to fool close friends, able to fool yo mama.

My father’s brother is the spitting image of Clint Eastwood. They’re about the same age, and they looked alike in their 20’s, and they look alike still. The biggest difference is that Uncle Bob is laid back and smiles a lot, a big departure from the Clint Image. (Who knows though, in private life Clint might be laid back and smile a lot!)

However, I’ve never heard him say “Feel lucky, punk?” or “Go ahead, make my day!” He doesn’t have the voice, either.

Hilarious! But, stay away from where I work, please.