Mark Zuckerberg's efforts to keep his company relevant to people the age of his own children continued today with Facebook's launch of Messenger Kids, a standalone iOS app for the sub-13 set.It's Facebook's latest concerted attempt to grab the attention of Generation Z, the kids who are mostly still less than 21 and already comprise more than a quarter of the U.S. population.Though Gen Z uses Facebook as something of a public utility, like proving to a faraway grandmother that they actually did wear that Christmas sweater because even she uses Facebook, it's pretty clear the generation has other preferences when it comes to social media apps.As I wrote about a month ago, Most Favorite Gen Z App status belongs overwhelmingly to Snapchat, tabbed tops by nearly half of all teens, according to a semi-annual study by Piper Jaffray,Facebook, by contrast, was the favorite of less than 10 percent of teens, though its Instagram app has held on to second place through several surveys, albeit at roughly half the level of Snapchat.To further bolster Facebook's mediocre relationship with teens, the online giant recently scooped up tbh for an undisclosed price, just a few weeks after the "positivity" social-media app first launched on the iTunes Store to a toasty warm embrace from kids tired of dodging Facebook trolls.Now Facebook is heading even younger, with a home-grown junior version of its widely used Messenger app. Messenger Kids, the company says, lets "Parents have more control" and "Kids have more fun," all inside the cocoon of the parents' Facebook account.Messenger is already huge, with more than 1.2 billion users worldwide, as of April. That makes it one of the world's biggest messaging platforms. Trying to wire Junior into the Messenger ecosystem at a young age, while avoiding issues with COPA and other regulatory controls on marketing to children under the age of 13, certainly makes lots of sense for Facebook. If it can get kids into the ecosystem, then the natural lock-in advantages conferred by the Network Effect give it a powerful foothold among youths before they've even hit puberty. It's arguably kinda evil, but almost certainly brilliant.That said, I'm not sure how enthusiastic children will be about hopping onto the Messenger Kids train. Facebook touts that one important feature of the app is, "Messages don't disappear and can't be hidden in case parents would like to check in." Snapchat won the love of the young precisely because it didn't save messages.And Facebook promises the free app will have no ads or in-app purchases, which is both attractive for watchful parents and says how much Facebook is willing to sacrifice, at least for now, to get younger users wired into its systems, riding along with their parents' Facebook/Messenger accounts.That said, I'm not sure how much anyone believes Facebook when it says it won't be monetizing one of its services. Its history of monetization, from the start and ever since, has been a question of "When?" not "If?"Will the Messenger Kids gambit work? To some extent, probably. But having an account that can be watched over and controlled by a helicopter parent is a great way to ensure Messenger Kids remains a totally not-cool option as children connect to the digital world unfolding around them. Hard to see how that plays out with a big win for Facebook.