I was born when my granddad was 75 - not too extraordinary, but all my friends had much younger grandparents.
More remarkable is my granddad's own grandfather, who was born about 90 years before him. He married (for the second time) at age 60, his daughter (my great-grandmother) was born, then he died shortly afterwards. My granddad was born 30 years later.
Even more remarkable is that my great-great-grandfather had been married before at age 20 and was already a grandfather in his early forties. So my great-grandmother had a niece who was about 20 years older than her!