I've noticed that when I read the obituaries of prominent people in New York Times, I always check the last paragraph to see how many grandchildren they have. The replacement rate would be four, and lots of high-achieving people die without getting to that number.
On the other hand, I just noticed that golfer Jack Nicklaus (who is not dead, by the way -- his name just comes up whenever there's a major championship), whose career record of 18 major championships is looking more secure each month (Tiger has been stuck on 14 for just under three years), has 21 grandchildren.
Nicklaus, who was born in 1940, had six children, and his children have averaged 3.5 kids each, which is a lot for a celebrity's kids these days. (I suspect that bequests from Grandpa Jack have helped his offspring go forth and multiply.)
Nicklaus is an example of high all-around competence. For one thing, he was a fat white 5'10" kid who could dunk a basketball. He's also one of very few celebrities to lose a large amount of weight for cosmetic purposes in mid-career without hurting performance.
I'm not sure that I'd want to have Jack Nicklaus as my next door neighbor. (I suspect he would roll his eyes in a marked manner at my lawn care efforts.) But, in case of, say, alien invasion, I would be glad that there were more rather than fewer copies of his genes floating around in the human race.
It might be interesting for somebody to go through obituaries of high achievers and build a database of numbers of children, grandchildren, and great grandchildren.