Well I agree with having genetic tests done if the inheritable diseases you are talking about are life endangering. However if it's something where children could still live a normal life like PKU I wouldn't let it stop me from having kids.

I am slowly nearing the age where I have to decide what is the best for my children. I have some family history of a couple of heritable illnesses and so does my soon to be wife. What can I do to make sure that the children have the least probable chance of getting these issues?