I wish I had the forethought then, but I was a teenager/early-adult and wanted to know my ancestry after learning my father is actually my step-father.

Did the test and to be honest, have no clue of its accuracy, my brother is in the same boat and didn’t know his biological father and did the test as well and 23andMe immediately picked us up as brothers.

It’s cool at first but then once you know you’re like, “well that was that” and move on.

how would you approach gene testing in a way that maintains privacy, at this time?

Data of just ethnicity or heritage (as in area of family origin) itself already special protected data under EU GDPR, not even allowed store without special permission. Let alone connect with other people.

In germany test for fatherhood is illegal without consent of all party or judge ordering one. So unconsenting gene match for fatherhood probably also illegal.

All in all, probably impossible. This data will ruin more life than the joy it bring to know some random fact about heritage.

If a family member has done it, your privacy is already gone.
I had a new sister turn up out of nowhere. I've never had any genetic testing.

They just need about 5 of your third cousins to take the test and they can pin your DNA down

There are hospital/clinic genetic consultations you can do as well. 23 and me is specifically non-diagnostic and for ancestry/tracing. Thats why they have all these loopholes around information protection and whatnot. Genetic counselling is much better regulated/must abide by privacy laws and a healthcare professional can help walk you through your predispositions and risks. source: I did a mini-project on this for my med lab program. There is a pretty shocking gap between clinical genetics and direct to consumer DNA testing, I wouldn't touch the private industry with a 10 foot pole.

Ask your medical care provider about genetic testing. It's a lot more affordable these days, and you should get a report on any genetic conditions you might be susceptible to. This keeps the test results within your medical record, with all of the legal protections that apply.

Of course this won't try to match you up with unknown family members like 23&me, but you can't really do that and have privacy because it requires broad analysis of all available test results.

I didn't want to do it, but my wife and parents thought I was being over worried and not fun. and then they bought me a kit even knowing I had reservations. Eventually I gave in and did it just to get the kit off the kitchen table and get them to leave me alone.

Welp.

I too am in the same boat and would kindly like to know the answer to your question!