Dad was one of 16; Grandad maternall 11.
They were rare even then.
Eighteen is so rare now that it gets headlines.
That says it all does it not? Extremely rare.
Dad was raised by siblings. Now his childhood was an awful one- extreme poverty (hedgehog casserole anyone?) but they've mostly done OK for themselves and the siblings saveed it for them i think.
Although many of the elder siblings had zero kids which possibly says a lot.