Lets face it technology is here to stay. There is nothing inherently wrong with having a social networking account to talk to grandma and grandpa, close family friends, etc. What is needed is parental rights (i.E. Administrator rights) that allows parents to monitor what is happening and guide them through the process. Its an educational opportunity, and a means of introducing technology in healthy way, while having parents there to protect ... Just like they do with every other social activity out there. This one is no different - and grandma and grandpa appreciate notes from the grand kids.
I think 10 year old kids and below it can have social media accounts, if he's or she's mom or dad is watching he, when he uses social media. I know it's against many social media rules but i think its okay when mom or dad is watching the kids when they use social media!
Their minds still in the process of development, and exposing them to internet can do them serious damage. They are vulnerable and have no idea how to deal with bullies and strangers who can possibly harass them online. And they can learn about things which they are not supposed to. Let them enjoy their childhood without all the gadgets fuss.
Children below the age of 10 should not have social networking accounts as they are still not mature and could be ''lied'' by the strangers on the internet. They could also chat with strangers that maybe their wallpaper picture is a friendly guy but the actual person is a liar to kids.