I think you're confusing between child labour and simple activities between parents and their children, such as your father/mother teaching you how to fix something (and doing so regularly).
From the Wiki article i just linked you to:
In many developed countries, it is considered inappropriate or exploitative if a child below a certain age works (excluding household chores, in a family shop, or school-related work).
and from the same link
boycotting products manufactured through child labour may force these children to turn to more dangerous or strenuous professions, such as prostitution or agriculture. For example, a UNICEF study found that after the Child Labor Deterrence Act was introduced in the US, an estimated 50,000 children were dismissed from their garment industry jobs in Bangladesh
Child labour - Wikipedia, the free encyclopedia