When you list dependents, TurboTax asks in the personal information section for your dependent's information including his/her SSN. If someone else uses your dependent's SSN in the future, you may receive a letter from the IRS. I am not 100% sure about this, but the IRS does send a letter to both parties if two people claim someone as a dependent in the same year. You could call the IRS help line and ask for more details.
