From the moment a child talks it means that they have been listening to what you say. In my understanding, adults tend to complain a lot in front of kids not knowing that the first instinct of a child is to mirror the behavior of others. I believe that adults should be careful when talking about big issues in front of young children because they will pick up this negativity and, over time, become negatively programmed themselves. However, you should never shield kids from world events. I recommend adults to level with the kid in an age-appropriate and reassuring way because they are powerless to address anything in their life but have the right to understand that there are certain things that can affect them.