Scientific investigation starts with an observation of a natural phenomenon or problem. What observation prompted the family to conduct a scientific investigation?

The observation of an disorder or disease which occurs in unnatural manner prompted the family to conduct a scientific investigation.

Explanation: A scientific investigation is a process to solve or identify the cause of problem in a specific manner. This method is actually the testing a hypothesis which is a statement based on the observation. For example, the continuous occurrence of fever which is caused by mosquito will prompted the family to investigate that the fever can be the result from dengue virus which is transferred through mosquito bite.