Q. Does a child under Bar- or Bat-Mitzvah age have to sit shivah if, God forbid, a close relative passes away?
A. The custom is that they do not sit shivah. Shivah is not only in order to honour and commemorate the departed, but also to arouse the mourners to repentance for any sins they may have committed. Since children under Bar- and Bat-Mitzvah are not yet of an age to be responsible for their sins, the obligation of sitting shivah can not be imposed upon them. However, they should still cut k’ri’ah (i.e. make a tear in their garments) and curtail their normal activities.