The Curliest Hair is the most fragile hair

Yes! The more twist and turns that your hair has, then the more opportunities for breakage. "Natural hair" is included.

If you think about the scales of a fish, when the scales are flat and tight, the fish is the most protected, smooth, and shiny.

Those scales are like our hair cuticle. If the hair cuticles are tightly closed, then they are the shiniest and beautiful.

Curls represent opportunities for the hair cuticles to raise up because there are so many twist and turns. Therefore you see frizz and some vulnerability because a tight cuticle keeps the hair protected.

Tight cuticles can be achieved through relaxation of the hair which is permanent straightening of the hair or by putting a polymer such as Brazilian Blowout Keratin Treatment around the strand which is temporary. Some people are born with straight hair.

If you decide on permanent relaxer, then the curliest hair will have the most bonds altered within one strand. If you go to the website: http://www.livestrong.com/article/41191-hair-relaxers/
it explains how the relaxer is designed to seek out the points where the hair bends in order to straighten it. So less bends equal less permenant alteration of the hair.

Those born with straight hair but use a lot of permanent color can find that they damage the cuticle therefore they see frizz which is a raised cuticle. The Brazilian Blowout Keratin Treatment again would be a good way to enclose the hair strand with a polymer to keep the cuticle down.

Overall, straight hair that is not continuously over processed where the cuticle becomes damaged is the healthiest, shiniest hair!