Differences in traits such as hair texture are determined by differences in

the genetics and DNA

Explanation:

Differences in hair texture mainly comes from our genetic, but more specific from our DNA. We could get the trait from either our mother or father or both. It depends on the shape of the hair follicles in our head. The genetic factor plays the major role in determining the hair texture. For example, if the child comes with recessive genes from the parents then the outcome could be a complete opposite outcome (parents with curly hair could have kids with straight hair). At the end it depends on how strong the genes are.

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)