Kids adore their new robot siblings.

As millions of American families buy robotic voice assistants to turn off lights, order pizzas and fetch movie times, children are eagerly co-opting the gadgets to settle dinner table disputes, answer homework questions and entertain friends at sleepover parties.

Many parents have been startled and intrigued by the way these disembodied, know-it-all voices — Amazon’s Alexa, Google Home, Microsoft’s Cortana — are impacting their kids’ behavior, making them more curious but also, at times, far less polite.

In just two years, the promise of the technology has already exceeded the marketing come-ons. The disabled are using voice assistants to control their homes, order groceries and listen to books. Caregivers to the elderly say the devices help with dementia, reminding users what day it is or when to take medicine.