Why do the Duggar Girls have such lovely hair?

They revere the teachings of a recently discredited religious leader, who has been, on occasion, called cultish and oppressive. (And interestingly, for a guy who was all about marriage and family, he was unmarried but creepy). To wit, from a website of people recovering from a life where they were forced to follow Gothard's teachings:

Gothard was not shy about what he found to be attractive on a woman's head–long hair, soft curls. I heard girls reacting to that all the time. There were girls who couldn't get their hair to hold a curl. One friend said to me, "Look how limp my hair is, and I had it all up in hot rollers just two hours ago!" Others couldn't grow their hair long or just preferred it short. Still, they knew they weren't living up to Gothard's ideal. Some girls probably weren't bothered at all. I heard more from the ones who were.

Well I wanted to meet that ideal, and I did. I had plenty of insecurities, but my hair was my one glory, my one claim to beauty. I could make it do whatever I wanted. Add a little navy and white and some bright eyes, and I could achieve the perfect ATI (Advanced Training Institute) look. Yes, other girls were jealous of my hair. I know because they told me. As an ATI teenager, I couldn't talk to boys and had to go skiing in a skirt, but at least I had great hair.

So like, is Jessa rebelling here or what?

Why do the Duggar Girls have such lovely hair?