My mother was born in 1914, my DD is her youngest grandchild, born in 2007. (That kind of spread in the female line isn't at all unusual in my family; we have great fun making doctors' jaws drop. They usually want to go for the DNA swab right after that.)
As for cousins, I'm not precisely sure, but my oldest sister was one of the first in that generation, born early in 1940, and the last cousin in my generation is in her late 20's now, so about 53 years. In my immediate family my sister's eldest was born in 1962, and again, my youngest in 2007, so that's 45 years. (We are all full siblings, btw, no one with multiple marriages.)