The smartphone has become the dominant piece of technology of our age, sucking even more of our attention into its brilliantly engineered clutches. It's bad enough for adults - hold on a sec, I just got six Slack messages - but keeping the phone from warping the brains of young kids can be a challenge.My 2-year-old twins are constantly grabbing at my phone because they see me doing the same - stand by, I've got to reply to this group text - and they like the way it lights up.