My genealogy goes way back from others studying it. I know all of my first cousins and most of my first cousins once removed. And in touch with all for some years. My husband's goes back to 800 AD. See no reason for my DNA or his to be out there for anyone to do with whatever they want.
I think in the coming years, it's going to be a scary scenario for many because they put theirs out there. Just like all medical records now online for anyone to hack into. And they will. I'm old now, my grandparents all lived into their 80's and 90's along with great aunts and uncles. My mother turns 96 today. As someone else said, we will all live until the day chosen for Our Maker to call us home.