Answer 1: One of the parents has a dominant gene, and if a dominant gene is inherited you could get a genetic disease.

Answer 2: It is possible for two healthy parents to have a child with a disorder if both parents are carriers for the disorder For example, in recessive disorders, the carriers dominant gene would mask the recessive allele and the only way for the child to be affected is if both recessive alleles are inherited.

Answer 3: It is possible for two healthy parents to have a diseased child if one parent is a carrier for the disease and passes the affected allele to their kid.