Just imagine that a woman has about 10 children, then forced them to have about 5 grandchildren per child. Now she has a gang. And all of that only because she wants to have full control over the neighborhood /s
There isn't much detail in the English article, but to give you an example of how crazy things got, the 25th child of a family had free education... The average was 14 child per family at its peak! French Canadians in New Brunswick went from 15% to 40% of the province's population over a century even if french immigration was basically non existent while English immigration was...
You make it sound like bad to have a family gang.
It has so many uses, great for ilegal stuff, great for polítics, great for business, it is all benefits of controlling up to certain point a large group of people and having a strong link with them.