One example might be the BRCA gene mutation. It gives you a higher chance of breast cancer and is typically associated with Ashkenazi Jews.

I'm sure your insurer would be interested to know if you have it, and that potentially your children are at an elevated risk.

Unfortunately there might be people interested in the ethnic association as well.

You got a point, but from a different angle is it ethical to hide your medical data from a company that may end up paying all your medical bills? It's almost like how people hide finances, you hide it because you want to do something unethical.

If I was jewish, I feel that right now I would just be slightly worried for myself. In general I wouldn't be too worried at all. I would, however, be more worried for my jewish kids, they may have to deal with that stuff in the future.

Although I would worry, I would question whether my worry is based on ethical grounds as that part is not clear.