1. Pluck one gray hair and two grow back.
Not true, it doesn't at all. It's better color your hair than pluck.
2. Cutting your hair makes it stronger or grow faster.
Although this may seem the case for men's facial hair, the hair on your head has different properties. Hair just naturally follow its cycle of growing around half an inch per month, regardless of how often you cut it.
3. You can fix split ends.
Unfortunately, no. If you see split ends, cut it because it can cause more damage by splitting more towards the scalp.
4. Tight hats cause baldness.
This one is interesting and I know where it started. In the military, men wear tight hats and started balding. In reality, it was just the timing because men entering military are usually at the age where balding starts. Dihydrotestosterone, not hats contribute to balding!
Actually it can cause split ends so only brush when necessary. As soon as it is tamed, stop!
6. Sometimes hair can turn gray or white over night.
Nope. It takes a long time for hair to change color. It doesn't really turn gray or white, it is more caused by the loss of color in your hair.
7. Baldness is inherited from the mothers side of the family.
Nah, it can come from either side. Hair loss usually begins at age 18 to 20 and the rate increases between age 45 to 55.
8. Dry scalp can cause dandruff.
They are two different things. Use shampoo and conditioner for dry scalp but dandruff shampoos are not necessary for dry scalp.
Funny. It isn't but do not share combs or brush!
10. Cutting your hair during a full moon makes it grow in healthier, fuller, faster or longer.
No way, cutting hair doesn't do much to the hair at all except make it shorter.
Adapted from: http://www.hair-styles.org/top-10-hair-myths.html