Regardless of what makes your hair appear frizzy, the underlying cause is usually the same: a raised cuticle layer. As a result, the hair looks dry and frizzy instead of laying flat. On the contrary, the hair appears smooth when the cuticle layer stays flat.
Curlies tend to have frizz more often than Straighties for one simple reason: dehydration. In general, curly hair is drier than straight hair. This leaves our hair susceptible to frizz. Another reason stems from the way we style our hair. As Curlies, we have to be extremely careful NOT to brush our hair. If we do, we encourage the cuticle layer to rise up, resulting in frizz.