As someone who grew up thinking he wanted to be an attorney (until I realized how much paper work there was), I grew up participating in debate club and mock court. My sister grew up wanting to be a doctor and would research various illnesses and learn all about them; she is now in school for medicine. This sort of thing might not happen in every field, but the two you pointed to are probably not the best examples, since both of these behaviors are pretty common for kids interested in law and medicine.