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What Makes Hair Curly or Straight?

What Makes Curly Hair Curly and Straight Hair Straight?

And wavy hair wavy? Well, as you may have suspected, it does have to do with genetics, but other factors influence hair growth as well. According to Proctor and Gamble, researchers do not completely understand why some hair twists and turns and some lays flat, but here are the most commonly accepted theories. Some are a little more scientific and others more commonsense.
Check them out when you


  • Shape and opening of the follicle: If you have curly hair, your follicle is probably very flat in diameter. Straight-haired people have circular follicles. As for the wavy bunch? They have oval-shaped follicles.
  • The number of twists per unit length: Even the straightest of hair twists as it grows. The more twists, the more curl.
  • Humidity in the air: Hair, which is porous by nature, easily absorbs moisture molecules in the air, making the hair curl or frizz. Enough said.
  • Hormones and medication: Changes to the shape of the follicle caused by hormones and medication can alter the texture of your hair and the way it grows.
  • The position of the hair bulb in the follicle: The bulb is located at the bottom of the hair shaft. People with really curly hair may have a hooked end towards the bottom of the shaft, meaning their hair grows at more of an angle. Straight hair means little to no hook.
  • The number of disulfide bonds in the hair: Simply put, the way protein structures are arranged in each hair shaft effect how hair behaves. The more disulfide bonds that occur between hair proteins, the curlier the hair and vice versa. This explains why you can temporarily alter the texture of your hair with heat and/or water — just by breaking bonds.


Join The Conversation
ClearSkinDiva14 ClearSkinDiva14 8 years
I remember when I was litte I had really curly hair, then by the time I was 5 or 6 it went wavy. Even though my hair is wavy, it tends to get curly after I wash it. In the summer, ringlets can form because of the humidity. Maybe it has to do with genetics, since my mom has curly hair, and my dad has wavy hair, so I got a combination of both.
demi-serena demi-serena 8 years
yea my bros have curly said mine would eventually go curly after he when from straight to super curly when growing up.i still havent gotten that curly hair ,sigh i want atleast wavy like the rest of my family
TwistandShout TwistandShout 8 years
I'm blessed with some beautiful curls that appeared immediately post-puberty. When I was a kid I had the nastiest, thinnest, straightest hair you'd ever seen. Now that it's curly, it's still thin, but nobody can tell ;]
witchbaby witchbaby 8 years
my hair is super wavy if I let it dry naturally i love it and hate it at the same time. :\
ThePerfectScore ThePerfectScore 8 years
I am 4 months post relaxer.... I know about curly hair! I love the texture, the way it feels, but it just takes forever to detangle. I have to do it under the shower with tons of conditioner in my hair. I don't think I will transition to natural no matter how much I love the waves and coils.
SKC-Sparkle SKC-Sparkle 8 years
Interesting...I have curly-frizzy hair. If it behaves, I love it, but most often than not, I look like I got electrocuted. :(
GlowingMoon GlowingMoon 8 years
I agree -- interesting article. I have thick, straight hair. These days, now that I know how to take care of it, I love it. Healthy hair is a great accessory, I think. :)
La-Heidi La-Heidi 8 years
its true about hormones. when i was young, i had straight hair but once i got my period it started getting wavy once, curly once but mostly unstraight. now that my hormonal changes are a bit steadier, my haur's gone straight again
queenegg queenegg 8 years
Interesting. I just wish that my super straight, super fine, super lazy hair would do something. Maybe it get dizzy after a couple of twists and refuses to do anything. (Please forgive if that doesn't make sense. It's been a long day.)
genesisrocks genesisrocks 8 years
emalove emalove 8 years
Interesting...I never really thought about this before!
rc4480 rc4480 8 years
kind of cool. i like the science-y articles, bella :)
prencesschris prencesschris 8 years
very interesting...i like this *article*
Pistil Pistil 8 years
I think hormones can produce permanent changes.
Evalicious Evalicious 8 years
Can you tell me why my hair was curly before I had my daughter and is now (she's 1 1/2) stick straight. I know pregnancy and hormones change, but it's been almost 2 years and nothing changes.
aimeeb aimeeb 8 years
So neat to know!
miss-malone miss-malone 8 years
Interesting... mine is somewhere between straight and slightly wavy. I love it.
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