How do I make my hair thicker/nappy for dreadlocks?

Ok, this may sound weird, but as far as I know, I'm completely African-American but my hair is really straight naturally. About 8 months ago, I put my hair into tiny braids to start my locs, and from the very beginning they were really straight but I wasnt worried; I figured they would start acting Black after a while. Now, months later, my hair still looks like braids-old braids with a perm in my hair. The ones in the back of my head are starting to lock up, but its really frustrating me that on 'regular' African-American hair, the braids would have locked up by now. Any ideas on how I can make my hair thicker and/or nappier to get my hair on the right track?? Serious comments please!!! Anyone anti-dreadlock please dont bother putting up a comment!!!! Thanks