Apple says the iPhone X's facial recognition system isn't for kids

One of the hallmark features of Apple's new iPhone X will be its facial recognition technology.

But that technology, dubbed Face ID, won't be for everyone.

Apple says that Face ID for children under 13 may be less accurate, the company warned consumers on Wednesday in a newly released document offering new details about the technology.

The facial features of those under 13 haven't completely developed yet, the company explained. Apple's facial recognition technology can adapt to the small changes people's faces undergo over time. But the bigger changes that children's faces go through are much more likely to stump Face ID and increase the probability that it will get a match wrong.

"The statistical probability is different for twins and siblings that look like you and among children under the age of 13, because their distinct facial features may not have fully developed. If you're concerned about this, we recommend using a passcode to authenticate," according to an Apple support article posted on Wednesday.

Face ID relies on a new kind of camera system that's built into the iPhone X, Apple's new flagship phone that's scheduled to hit stores in November. To identify users, the camera system takes a 3D scan of their faces. The iPhone X relies on Face ID instead of a fingerprint scanner.

Instead of Face ID, Apple recommends young iPhone X users rely on a passcode or password to unlock their phones.

Apple is serious enough about Face ID being unsuitable for young users that it's barring app developers from allowing younger consumers to use Face ID to log into their apps. It updated its App Store review guidelines earlier this month to reflect the change.

Younger consumers aren't the only ones Apple is discouraging from using Face ID. The company also recommends that people who have identical twins or those who have siblings who are often mistaken for their twin might also want to use a passcode instead.