Your DNA is just a rich mine of new data points about you that they can exploit and use against you. Maybe AI thinks you're more likely than most people to have medical issues and as a result companies now refuse to hire you. Maybe AI decides that your DNA makes you more susceptible to certain addictions or alcoholism and companies selling addictive products target you relentlessly as a result. Maybe your DNA makes AI think you're more prone to criminal activity and the police harass you endlessly until you either end up in prison or move away.
The conclusions AI reaches don't even have to be scientifically valid, they could be nothing more than hallucinations, but that doesn't mean that it won't have impacts on your life or place limitations on your opportunities.