Eli5 why genetic diversion between several groups of people is less than within one

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I saw it mentioned in several books that, for example, I’m (as a human, who I totally am) more genetically diverse to people living in my country than to people living across the ocean. How can you explain it or did I just get it wrong? My brain (of course only one, as we all have) can’t understand it, because the opposite seems more reasonable.

Btw we love this sub. Thanks.

In: Biology

I think this more to do with there being more differences within groups than between groups. So it’s not that you, as an individual, share more in common with someone from a different group than with someone from within your own. It’s more that differences within one group can be large but that average difference between groups tends to be small.

Genetics is kind of complicated so think of it like something else. Men tend to be taller than women. In the US, the average man is 5’9 and the average woman is 5’4. An average difference of 5 inches. But within those two groups there can be very big differences. So you can have a women who’s 5’9 and another woman who’s 5’0 – a difference of 9 inches. It’s not unusual for women to be these heights. So there can be much bigger difference between individuals within the group than there is, on average, between the two groups.

> (as a human, who I totally am)

love it, haha

They mean that to define a type of population, you establish averages. If you average the height of every American and compared that to the height of every Brazilian, you’d see that on average people in the US are taller than people in Brazil. There’s a genetic component to that and it explains the delta.

The part you’re asking about however, is that within America, the range of possible human heights is massive. Even though Shaquille O’Neal is American, the difference between his height and my height is far larger than the difference between the average American height and the average Brazilian height, or even between my height and any given random Brazilian.