how many siblings?

in the past, families used to be big, across the world. 100 years 
ago many babies died, it was normal. it was normal to have 5-12 
children i guess.

i could never have 12 children, zero is enough.

but that's the thing, across the world, it is now normal to have 
1-2 and often none. if someone has 3 or more, they are weird.

my great grandfather had 8 children, that i am aware of.. they 
have spread across the world. i suppose that has had a bigger 
effect on the world than any one normal person doing one very 
significant thing.