( CNN ) -- Until this week , how many parents paid much attention to `` Slenderman '' ? He was a fictional villain in a wildly popular online game of hide and seek -- a tall , thin , and faceless monster with tentacle-like arms featured in Web-based ghost stories created by and for horror story enthusiasts . But that 's where this story takes a very dark and tragic turn . With the arrest last weekend of two 12-year-old girls in a suburb of Milwaukee for the alleged stabbing and attempted murder of another 12-year-old girl -- their friend -- it seems that the made-up meme could have inspired monstrous acts in real life . The young suspects were arrested after allegedly luring their innocent friend into the woods and stabbing her 19 times , according to authorities . And a criminal complaint says the suspects admitted they were trying to impress `` Slenderman , '' whom they read about on a horror website . But there is so much more to this story that parents and kids need to talk about . As the founder of a national nonprofit who has spent the last 10 years dedicated to helping kids and teens thrive in the digital world , here 's what I know is true : We are raising our children in a hyper-connected , always on , and ever-evolving media and technology landscape that offers many opportunities , yet many challenges for families . In effect , we are conducting an experiment on our children in real time , and how it turns out for them depends a lot on us . It 's very hard to keep up with what 's new and what 's popular with our kids , but the risks of not getting and staying involved in their digital lives is too high . Here 's why : . The world of media is a super peer . It can influence our kids ' social , emotional , cognitive , and physical development , and it can powerfully inform their sense of what 's normal and acceptable . Stories , characters and their behavior in media -- whether in a video game , a movie , a TV show , or on a website -- can serve as role models , both good and bad . Do you know what your kids are watching , reading , and doing online ? Do you know who shares their conversations and who plays in their games ? And above all , are the media they 're choosing appropriate for their age and developmental stage ? Mature content may not be suited to immature and developing minds , especially in children , who often can not comprehend the difference between reality and fantasy , and who can not understand the consequences of violent acts . Media can be an amplifier in people , including children , who are at risk . Much more research is needed on the impact of violent media on behavior . But existing research suggests that people who are prone to violent actions , or depression , or anxiety , feel those feelings more strongly , or may be motivated to act on them , when exposed to violent content . Research also points to a correlation between repetitive viewing of violence and increased aggression and desensitization . The research is also uncovering a `` reciprocal '' relationship in which children with aggressive tendencies do , over time , seek out more violent media content and are even more affected by it than others , thus creating a downward spiral . Slenderman stabbing case : When can kids understand reality vs. fantasy ? Parents are key to combating the negative effects of media . Our children are exposed to a great deal of content that may not be worthy of their time and attention . Even if your family limits certain unacceptable media at home , your kids can access that same content on any mobile device when they 're not at home or with you . That 's why it 's imperative to engage with them about the media they 're consuming . Take the time to elicit your kids ' opinions on what 's popular and what they 're interested in , and share your opinions so as to help your kids develop the ability to view media critically and make choices that reflect your family 's values . Every child and every family are different , so what works in my family may not work in yours . Each of us has different pain points , different views on what 's appropriate , and different opinions on how much is too much . The reality for all of us , though , is that what happens online can influence what happens in real life . Parenting needs to happen in both places . That way our kids can thrive , even in the face of a made-up monster in a dark and digital world .
James Steyer : Until 12-year-old 's stabbing , not many parents knew about `` Slenderman '' Steyer : Internet is a super peer that guides kids ' development , informs sense of what 's normal . He says media can offer good or bad role models and amplify problems in at-risk kids . Comment: Parents are key to combating negative media : Engage with your children .