Re: Projection much?
If you want more words of explanation, look up: 'The Inevitable Eve'.
On average, couples have about two kids. Each kid has one-half of the DNA from each parent. Two kids, each with 50% of each parents' DNA, independently selected of course, = 75%. Thus about 25% of *your* (keyword: your) DNA will not make it to the next generation. YMMV, it's based on typically two kids.
It's not "extinction", it's an extinction *RATIO* of about 25%. (Leave out words and yes you'll be confused.) MLER relates to mtDNA topic.
It's really trivially obvious that if each of your kids has only 50%, then two would get you to 75%, etc. You'll never get 100%, but you might get close with a dozen.
Taking into account gender, there's obviously a maternal and paternal lineage extinction ratio; no room for argument. Witness the antics of Henry VIII trying to overcome PLER and bad luck. The concept is trivially simple, but it and its implications have not yet been widely hoisted aboard.
And yes, there are secondary and tertiary effects. This is merely the primary effect.