Declining numbers

My wife and I are anticipating our 15th grandchild in September. To many people today, that seems remarkable, but to me it nothing particularly noteworthy. I am one of 32 grandchildren. My parents have 22 grandchildren. We have almost 15, so you can see the declining line. To take it back another generation, I know a man from Georgia in my grandfather's generation who was one of 45 grandchildren born to three brothers who lived within a three mile radius.