Look at the labels. The age range on duplos is 1.5-5, while normal legos are 5+ (with the exception of some sets). Connect the dots, everyone. What are duplos for? And besides, I've seen p-lenty of creations by 2 and 3 year olds. A spaceship: a simple plate with mismatched wheels, random minifigures, a steering wheel, and the occasional mismatched turbines (they don't know how to use all the good pieces). While a 5-year old's space ship sports fins, wings, spacemen instead of car drivers, a cockpit, matching wheel sets, proportional engines, some aerodynamic design, and a color scheme.
Mid you I had duplos long before I got my first two lego sets at age 4 (I wasn't the average kid then and never will be), at the same time my brother got his at six (He's....... Almost normal).
Stay in your own yard, play in your own yard, be happy in your own yard...No shadow viking, no it is not okay wether they swallow it or not.
PARENTS TAKE NOTE: 2 year olds

, please play with stuff for 2 year olds. Not every thing is a one-size-fits-all deal in the entertainment and toy world. in other words,
Stay in your own yard, play in your own yard, be happy in your own yard... (lyrics by Johnny Lang).