At the end of Return Of The Jedi, Vader threw Palpatine down one of the many bottomless chasms that are all the rage with far-far-awayist architects. If we're talking percentages, then that one act brought the numbers from Sith: 2, Jedi: 1 all the way to Sith: 0, Jedi: 1. You might recognize that as 100 percent of the Force being Jedi now, which is about as far out of "balance" as you can get.
So how could he have been the Chosen One? What's so special about grouchy-ass Anakin? Well, he has kids, but that's not special. That's basic biology and the result of Natalie Portman's mopey cuteness overriding his Jedi celibacy training. Once we all had our minds blown in Empire Strikes Back by Vader spoiling the results of Luke's paternity test, it kind of made sense, though. Of course Darth Vader is Luke's dad. Luke can use the Force, Vader can use the Force, something something genetics. Sure, let's all just accept this and not give it a second thought. Look! Boba Fett! The point is, we were kind of dumb in the '80s. But why should we assume that the ability to use the Force is genetic? If ability was inherited, then Michael Jordan's kids would be in the Basketball Hall of Fame, Ernest Hemingway's children would be Pulitzer winners, and Martin Sheen could hold his head up with pride.
Though to be fair, tiger's blood isn't any more or less stupid an explanation than midi-chlorians.
Unlike in the Original Trilogy, in the prequels, we see literally dozens of different Jedi. And yet Anakin's kids are the only examples of inherited Force use that we are shown or even mentioned. Sorry, fellow nerds, the Expanded Universe is gone, like a shared decades-long peyote dream. If our collective assumption that it was common for Jedi kids to inherit Force abilities was correct, then Yoda would have 900 years of grandkid Jedi, and surely the Emperor would have a few Darth Princes running around, ready for Pop-Pop to kick the proverbial Death Star. Hell, Palpatine knew that Anakin's unborn kids had gotten away, but he never gave it a second thought, because who cares? It's not like those brats could ever be a concern for him, right? He's got more power in the crow's feet on his forehead than the Rebellion has in its whole army.
The Old Republic had to screen all newborn babies across the entire Galaxy to see if they would randomly be born with the ability to use the Force, which seems inefficient if you could just notice when one of your own got pregnant instead. For that matter, the opening crawl of Episode II mentioned that there was a galactic Jedi shortage, which should have been impossible if Samuel L. Jackson could father them. Shmi Skywalker told Qui-Gon Jinn that Anakin was conceived by the Force itself -- though to be fair, this could have just been a deflection for a strange man on a dark rooftop suddenly asking about her sex life.
"You sure you can't give me any more details? Positions? It's all very important."