ACTUAL STATS:
I checked out
https://en.wikipedia.org/wiki/Category:Doping_cases_in_mixed_martial_arts
There are 104 doped fighters on that list.
22 are brazilans as far as I can tell after a quick count. T̶h̶a̶t̶'̶s̶ ̶1̶0̶%̶
Edit: that's 21%
Thiago Alves (fighter) - brazilian
Viscardi Andrade - brazilian
Ali Bagautinov
Josh Barnett
Phil Baroni
Vitor Belfort - brazilian
Joey Beltran
David Bielkheden
Stephan Bonnar
Brian Bowles (fighter)
Diego Brandão - brazilian
Alex Caceres
Cynthia Calvillo
Cortney Casey
Kevin Casey (fighter)
Rafael Cavalcante - brazilian
Donald Cerrone
Kit Cope
Wesley Correira
Mirko Cro Cop
Cris Cyborg - brazilian
Carina Damm - brazilian
Edwin Dewees
Nick Diaz
Robert Drysdale
Brian Ebersole
Ashlee Evans-Smith
Jessica Eye
Carlos Diego Ferreira - brazilian
Jon Fitch
Hermes França - brazilian
Riki Fukuda
Kelvin Gastelum
Louis Gaudinot
Fernando Gonzalez (fighter)
Lyman Good
Royce Gracie - brazilian
Melvin Guillard
Dennis Hallman
Pat Healy (fighter)
Dave Herman (fighter)
James Irvin (fighter)
Lavar Johnson
Jon Jones
Mark Kerr (fighter)
Cung Le
Chris Leben
Andrea Lee (fighter)
Kimo Leopoldo
Brock Lesnar
Héctor Lombard
Lyoto Machida - brazilian
Islam Makhachev
Rony Mariano Bezerra - brazilian
Nate Marquardt
Doug Marshall
Tim Means
Yancy Medeiros
Gilbert Melendez
Chad Mendes
Frank Mir
Jeff Monson
Augusto Montaño
Johnnie Morton
Pedro Munhoz - brazilian
Pawel Nastula
Emanuel Newton
Alexandre Franca Nogueira - brazilian
Brian Ortega
Alistair Overeem
Rousimar Palhares - brazilian
Karo Parisyan
B.J. Penn
Jessica Penne
Robbie Peralta
Vinicius Queiroz - brazilian
Jessica Rakoczy
Kevin Randleman
Jason Reinhardt
Mike Richman
Matt Riddle
Francisco Rivera (fighter)
Yoel Romero
Ben Rothwell
Junior dos Santos
Ken Shamrock
Sean Sherk
Jake Shields
Alexander Shlemenko
Kirill Sidelnikov
Anderson Silva - brazilian
Antônio Silva (fighter) - brazilian
Thiago Silva (fighter) - brazilian
Wanderlei Silva - brazilian
Dennis Siver
Kimbo Slice
Chael Sonnen
George Sullivan (fighter)
Tim Sylvia
Thiago Tavares - brazilian
Jesse Taylor
Gleison Tibau - brazilian
Francisco Trevino
Jim Wallhead
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Disclaimer:
* I have no idea if this list is complete, it's just wikipedia
* It includes all MMA orgs, not just UFC
* some cases are totally irrelevant, for example Nick Diaz and Kelvin Gastelum are on there just for weed.
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If someone has extra time feel free to cut the list down to UFC fighters only, filter out the irrelevant cases, and compare the percentage of brazilian offenders to the percentage of total brazilians in the UFC.