How many people are just like you?

And how many pieces of information could identify you? Are you a special snowflake?

I’ve been wondering about certain facts that describe each of us, some of which are just trivia about us, and some that largely define our situation and experience of the world. With each additional fact, the number of people in the world that share all those facts with you diminishes largely. And eventually with sufficient number of such pieces of information it’s possible to identify a person, because, likely no one else in the world shares all these pieces of information with you.

To make it all clearer, I’ll show it with my own example (Note, European style is used in Excel, so dot is for separating thousands, and comma is for a decimal point. )

Now of course, my estimates could be wrong, but it doesn’t really matter if they are. The point is that less than 10 not extremely rare facts about a person is usually enough to identify them. I am likely the only person in the world who is a male millennial, allergic to strawberries and strongly dislikes milk, is into classical music and meteorology, speaks 3 languages and has read “War and peace”.

Now, there is also another potential source of imprecision for this kind of calculation: these facts could be correlated. Perhaps most people who are into meteorology are also into classical music. Or most people who speak 3 languages have read “War and peace”. I don’t think the correlations are that strong, but they probably do exist. They would result in there being more people who are just like me, than the previous calculation would suggest. But I don’t think they affect the calculation that much. They could also be balanced by facts with negative correlation. I still think around 10 moderately specific facts would be enough to identify the person.

If you use more specific facts, you need even less facts to identify someone. For example, let’s try to guess the number of medical doctors who have multiple sclerosis.

Statistics says there are around 12,800,000 physicians (0.158% of the population) in the world. Also, there are around 2,800,000 people (0.034% of population) with multiple sclerosis. This would mean there are just 4,352 doctors with MS in the world (and probably less as MS can prevent people from becoming doctors).

Now, aside from identification, this kind of calculation can also be useful for determining how many people are “in the same boat” as you. You can make your own table in Excel, add formulas, and add a couple of facts about your situation or living condition that are important to you. If you can make a relatively close guesses about percent of people who are affected by each of these conditions, from this you can calculate how many are affected by all of them, or, in other words, are in the same boat as you.

This number is usually very small, and for this reason it’s quite unlikely to encounter a character in a film or a novel that resembles you in many aspects. Everyone’s story is quite unique.

Bonus: if someone accuses you of being a snowflake, you can cite this article to prove to them that you are, in fact, a snowflake. :) Not a special snowflake though, as you share this fact with 100% of people. We’re all snowflakes.