most genes dont match up......given your definition of genetic defects aperson with blue eyes(bb) doesn't have anything wrong with their genes but a person with brown eyes may assuming that the genetic pair is as such (Bb), then you really have to consider, variables such as codependant genes...(Bb)...where people have green eyes...or gold or grey etc.... really genetic definition doesn't really apply....perhaps you should think of a better arguement........and if this hasn't got to you...I can always go into hair color, hieght and so on......