Here's the breakdown:
* Hair shaft structure: Hair color is determined by the amount and type of melanin (pigment) in the hair shaft. While hair color doesn't directly influence oil production, thicker hair shafts tend to hold more oil. This isn't necessarily linked to color, but thicker hair is often associated with darker hair.
* Scalp oil production: The amount of sebum (natural oil) produced by the scalp varies from person to person. It's not determined by hair color, but by factors like genetics, hormones, and overall health.
Therefore, it's inaccurate to say that darker hair contains more oils than lighter hair. While thicker, darker hair *may* hold more oil, it's the individual's scalp and hair structure that ultimately determines the oiliness.