text: light-haired man blood type o..his wife dark hair blood type ab..her father had light hair? what is the probabiltity the child will have blood type a and dark hair? what is the probability that they will have a light hair child blood type b? there is a 1/2 chance that the child will have blood type a and a 1/2 chance that the child will have dark hair.  since these are independantly assorting traits the chance that the child will have both dark hair and blood type a is 1/4 (becuase you have to use the product rule).  there is a 1/2 chance that the child will have blood type b and a 1/2 chance that the child wil have light hair.  using the product rule again the chance that the child will have both light hair and blood type b is 1/4.