Nearly all Chileans have the same blood type

85.5% of people in Chile have blood type O+. This is the highest concentration of one blood type in any country. Ecuador comes second with 75% and Peru has 70% with type O+.

Blood type O+ is the most common blood type in the world (one in three people have type O).

AB negative is the rarest blood type, just 0.6% of the world’s population have this. Romania and Slovakia have the highest percentage of AB negative (1.2% each).

Why does Chile have such a strong concentration of one blood group?

The reason is not clear but Rick Wicklin, PhD, a researcher in computational statistics at SAS says the most likely explanation is immigration.

Many Chileans have mixed ancestry. There are many immigrants from Peru (Peruvian indians have 100% bloodtype O+) and many people of Basque origin, (Basque people also have a high percentage of O+). Of course this is just my speculation. Answers below please!

https://en.wikipedia.org/wiki/Blood_type_distribution_by_country