Dr. fletcher is attempting to determine whether adult criminals were rule-breakers throughout their childhood or whether they suddenly turned to a life of crime. her research is most concerned with which issue of human development

The answer is "continuity vs. discontinuity".

Normative development is normally seen as a continual and total process. The continuity see says that change is steady. Youngsters turn out to be more capable in considering, talking or acting similarly as they get taller.  

The discontinuity view considers advancement to be more unexpected a progression of changes that create diverse practices in various age-particular life periods called stages. Natural changes give the possibility to these progressions.  

Psychologists of the discontinuity view trust that individuals experience similar stages, in a similar request, however not really at a similar rate.