gregmah said:
They don't need to go.
"Who must go
Adults and children aged 14 or over must go to the citizenship ceremony and take the oath.
Parents will get certificates of citizenship for their children under age 14.
Children under age 14 do not have to go, but they are welcome to do so."
Source: http://www.cic.gc.ca/english/citizenship/cit-ceremony.asp