Based on the textbook's description of the inheritance of hair texture, can two parents heterozygous for wavy hair still produce a child with curly hair?

Heterozygous means that each parent has a dominant gene and a recessive gene. Using C as dominant for wavy hair and c for recessive meaning it will be curly, there is .25 that have CC, .25 that have cc, and .50 that have Cc. 

There is a 25% chance that parents who are heterozygous for wavy hair will have a child with curly hair. 

Strands of DNA are composed of the sugar and phosphate portions of the nucleotides, while the middle portions are made of the nitrogenous bases. The nitrogenous bases on the two strands of DNA pair up, purine with a pyrimidine (A with T, G with C), and are held together by weak hydrogen bonds. Internal and external hydrogen bonds maintain the DNA molecule. The two strands of DNA stay together by H bonds that occur between similar nucleotide base pairs. Two hydrogen bonds occur among the adenosine and the thymine base pairs, and between the cytosine and the guanine, there are three.