Despite their close genetic relationship and the ability to inter-breed, there are a number of diagnostic features to distinguish the gray wolves from domestic dogs. In the physical characteristics compared to equally sized wolves, dogs tend to have 20% smaller skulls and 30% smaller brains. The teeth of gray wolves are also proportionately larger than those of dogs. Compared to wolves, dogs have a more domed forehead. The Behavioral differences shows that Dogs generally show reduced fear and aggression compared to wolves.