If it is really 100% real hair you should be able too:
use hair straighteners
use curing irons
use hair dryer
colour the hair (better to go dark but this is due to processing of the hair)
If you are buying hair that is claimed to be 100% real human hair but cannot do any of the above, it is not 100% and only uses some human hair and to help fill out the pack they put in nylon and horse hair.