According to the Indiana code, a parent is ultimately responsible for supervision of their child until the child reaches the age of 18. Often parents leave their children unattended at an earlier age or allow children younger than age 18 to provide childcare for other children. Under the age of 18, the law gives parents discretion to make these decisions based on the perceived risk and weighing such factors as maturity of the child, physical environmental risks, etc. You can review the pertinent statute at the following web address: www.in.gov/legislative/ic/code/title31/ar34/ch1.html
Prevent Child Abuse Indiana has prepared a brochure on this issue which may be helpful. This brochure can be found at: http://www.in.gov/dcs/2330.htm (Home Alone Brochure)