You should also know that empathy and perspective taking and consequential thinking are all abilities residing primarily in the frontal lobes. This part of the brain is the last to develop both evolutionarily and developmentally, with or without ADHD.
Very young babies can be said to not have empathy at all, since they are the center of a world that revolves around them as an extension of themselves. The frontal lobes gradually develop through childhood and adolescence and continue to do so into the early to mid-20s, sometimes even later. That is a good part of why children, adolescents, and young adults seem to be so impulsive compared to older adults.