Amazon's Alexa devices and services is (are?) one of the major players in the home "voice" assistant market. Alexa can store recordings of your requests in order to build a "voiceprint" in order to provide more accuracy in responding to your requests, and to identify you and build a body of information about you.
And your kids, if they use Alexa.
Amazon says it only builds a database if the owner has given permission.
Registered users can prevent the building of the database by withdrawing consent. (Which is not exactly the same thing. Anybody got specific details on this area?)
Amazon also says that it doesn't collect information on children without parental consent. (But then, how does it know an individual is a child?)