What is the main reason some colonial children became apprentices and others worked on family farms?

In the 1700's there was two basic forms of work. 90% of the people were farmers and the rest were in business, on ships, building ships, tradesmen, worked in a factory, or professional like a lawyer. Many colonial children took over the family farm because they were raised to do that and the oldest son inherited the farm/plantation. This meant the younger brothers had to learn a trade or go into business. This is when a apprenticeship was sought. Ben Franklins father put him in an apprenticeship at 7 years old with a candlemaker, but t didn't work out. Washington was an apprentice to a surveyor. Some children learned and took over the family business and on ships there were boys as young as 10-12 years old who were ships boys or powder monkeys on war ships. They carried the gun powder to the cannons on the upper deck from the below deck. Lots of them died. The life of a colonial child was very different than today. In the colonies there was no " teens". They were babies and by the time they were 13 they were considered adults. So, they didn't go to school as long as we do and went to work sooner.