Is your voice truly unique out of the 8 billion out there in the world? Nobody could plausibly pass as you?
You might think voice is something you're born with. It's not, it rather partially comes from languages and your backgrounds. So random chances of someone literally sounding by DNA from half a world away is quite low.
Case in point - my wife has two twin brothers. Even though I've been interacting with them for over 10 years now, they sound exactly the same to me. If I close my eyes then there is zero chance I could tell them apart by voice alone. I know, it's an anecdote - but while I'm sure you could tell them apart by some really small thing that they do, to someone who isn't actively looking for those cues they are - for all intentions and purposes - the same.