Actually it’s Mariah’s grandpa (on her dad’s side) who is from Venezuela.
His family name is Nunez and changed it to Carey when he migrated to the US to avoid discrimination.
But she said it didn’t help much because Carey sounds very Irish and he was still suffering from discrimination (+ being dark skinned).
That’s what she said during an interview in Brazil or Argentina that you can find on YouTube.

Then her grandpa eventually met her grandma who was African-American.
And her dad was born.
Down the line her dad met her mom who is apparently 100% from Irish descents.

I’m surprised she barely talks about her latin origins nor never used such sounds in her music.