Yes damn near all
Man sherdog always has a lot of mental gymnastics with guys trying to claim American fighters
You could literally trace any American fighter to another country if you go back far enough lol But they are still American first and foremost.
Weidman has German and Irish heritage.
Stipe has Croation heritage.
Uriah Faber Dutch, Irish, Italian heritage
Nate Diaz Mexican and English heritage
Cain has Mexican heritage.
Randy Couture has French-Canadian (great-great-grandfather), English, some German, and Dutch heritage.
Luke Rockhold has English ancestry
Ronda has English, 1/4 Trinidadian and Grenadian (including African, Spanish, and English), 1/16th Polish, as well as German and Scottish heritage.
Forrest Griffen Irish ancestry
There all American, though. It's simply their ancestry.