Whooter, Why do you think insurance companies would want this information?
Because I think we will someday be able to tell very quickly at birth what our chances of acquiring certain diseases will be like cancers, diabetes, depression, substance abuse, chances of living a long life etc. based on our DNA. Insurance companies are sure to want to have this information and would mark each person and inevitably influence our lives financially.
Who will stop them from using the fact that Huntington's Disease or schizophrenia runs in your family ... as a means of charging your family higher insurance rates?
If you get charged higher rates, your employer will be privy to that information if your employer pays or contributes to your health insurance plan. Which, unless you are self-employed, is generally the case these days. That info may then, in turn, affect your pay scale and/or length of your employment.
What's the difference between relegating "undesirables" to a lower standard of life and just outright exterminating them? Some might even tag the latter option as the more humane one...
...Of course there is that unfortunate precedent which happened just before World War II...