Final answer:
The provided information does not specify the number of Newman's case studies that involve obtaining guns from a relative's home; therefore, an accurate answer cannot be given without additional data.
Step-by-step explanation:
The question asks how many of the 27 case studies included in Newman obtained guns from the home of a relative. However, based on the provided reference information, it is not possible to specify an exact number of case studies from Newman that address the issue of obtaining guns from a relative's home. The references indicate a broader societal concern about gun accessibility and the impact of mental health on school shootings, as well as the national debate on gun control, but do not quantify specific instances from Newman's case studies. Therefore, without additional specific information from the study by Newman itself, we cannot confidently provide the accurate number of case studies in question.