Oddly, a network's layout barely mattered. The number of nodes needed to control a whole network mostly depends on the average number of connections per node, the researchers found. Sparse networks, such as the regulatory system controlling genes in a yeast cell, are pretty resistant to control; roughly 80 percent of the nodes need to be influenced to get the desired outcome. Dense networks, on the other hand, such as many social networks, were much easier to control: Influence roughly 20 percent of the nodes and the whole network responds.