I barely had any hair on my head when I was two and three years old. My mother tape a small bow on the top of my head for a pix so people could tell I was a girl. I still didn't have much hair and it was thin and blond when I turned four but it finally started to grow and thicken up and it was curly, curly!! I'm 33 now and still have the same amount of curl.
My son was the same way until he was 3.