Elizabeth’s comment > Likes and Comments

And not know what the holocaust is, the civil rights movement, or anything involving biology. So basically she studied for a test.

The ACT test has no history or cultural components. There is no "studying for the test" that will have much impact. You can play games with testing strategies, but you can't "study for the test." You have to learn the material enough to be able to regurgitate it out at high speed. She obviously had learned enough biology that she was able to get do as well as her public education friends.
The fact is that her family valued education - it's apparent with the rest of the family. It's not extremist as all to not want to send your kids to public schools. The fact is that she got a good education at home - enough to perform so well later - including the concentration skills to perform at the levels of college she attended, and her brother talks about how their Dad was essentially responsible for him trying and going for his scholarships to college.

Very few people are smart enough and driven enough to learn as much as she learned through self-study.