Nope.
Curly hair shafts are SHAPED differently than straight hair.
I'm fairly sure what happened is that the oils in your daughter's hair are protecting the hydrogen bonds from reforming after having been denatured. The bonds break every time the hair gets wet, and then reform as it dries. When using a flat iron on curly hair (or blowing it out, or both), the hydrogen bonds are aligned straight. When the bonds get wet again, they break, and reform as curls. If the bonds can't get wet, though, because of the oils covering them... it will take them A WHILE to rebreak and reform again. (That's also what silicone humidity-protectant straightening products do... NOT relaxers which actually alter the bonds. The silicone cover the hair shaft protecting the hydrogen bonds between the proteins from getting wet.
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I have ringlets with a VERY strong curl pattern. I straighten my hair as a rule with a flat iron every day (I LOVE running my fingers through my hair). especially when it's cold out. When I switch back to being curly for a bit (summer)... unless I rock it out (process follows)... it's slightly less curly for about 7 washings (I wash my curls daily, or they dreadlock, I'm talking serious white-girl-curls). Then I'm back to the stupid stupid ringlets. I DO occasionally want those stupid curls back on day 1, though:
The process of rocking it out means TOTAL saturation (longer than a quick shower) to totally break all the hydrogen bonds, including washing twice (to strip it of the oils, which can block the hydrogen bonds from getting wet and reforming), then conditioning it and leaving it, then brushing while wet with conditioner in it, then twisting each curl, then rinsing, then gel (to help the hydrogen bonds reform AND not look like Mufasa), then twisting again.
All it does is ringlet me back up in a day instead of a week (Or, in your case... a day instead of... yike: 14 weeks if you're only washing every other week). Takes about 45 minutes. It's a pain. But I'm shirly temple'd up in an hour instead of a week.
I use VERY high heat, plus mild straightening chemicals, as long as I'm not doing actual relaxing (which takes over an hour, unless your husband was gone for a LONG time, then they didn't do that. ALSO costs about $400, so I'm pretty sure you'd notice)... and bam. It's back. Either in a single time of coaxing the hydrogen bonds back into their natural positions... or after a week of washing.
My sister's hair LOOKS as curly as mine, but she has a very WEAK curl pattern. When she straightens it (flat iron, not chemical), her hydrogen bonds don't reform as quickly. Even when she's all ringlet'd up... if she BRUSHES her curls, instead of spinning them, she's got wavy/straight hair. If your daughter has a very weak curl pattern, and quite a lot of oils in the shaft... it could concievably be months before all the bonds break and reform.
For a cheap gel option to help protect and reform those hydrogen bonds, I've had rather a lot of luck with Aussie Sydney Smooth... which is NOT a "curl" gel, but a slippery one... or with Garnier Fructis Curl Construct Mousse. If you want to spend a LOT of money there are better gels out there ($30-$60)... but for just getting the hydrogen bonds back in position, either of those 2 options- following some serious washing with a "clarifying" shampoo to bare the hydrogen bonds- should set you up.