A couple of thoughts on using DNA...
Be aware that scandals can be uncovered. My first cousin came back listed as my half sister. We are not quite sure what to make of this, but have agreed that we are not going to discuss it in the family until both of our mothers have passed away (both of our dads, who were brothers, are deceased). The skeleton in the closet should stay in the closet if somebody is going to be hurt by taking it out. There was also a story on the news this morning about a dad who turned out not to be the biological father of the daughter he and his wife had with the help of a fertility clinic.
If you are worried about privacy, you can always submit the test under an assumed name or initials. I'm the family genealogist, so in my family, I purchase and distribute the tests. This gives the test-ee a measure of privacy.
Know that the nationality percentages are wonky. There's a video on YouTube of three identical triplets - that's one egg split 3 ways - that got different results in terms of nationality. Ancestry blamed the Algorithm that they used.
That said, it did help us find a cousin/half brother who had been given up for adoption as a newborn, although it took tries with two different companies to find him. When we didn't find him on 23andMe, we tried Family Tree DNA. Amazingly, after 53 years, my cousin and her adopted brother both submitted their DNA the same month!
It has been useful in genealogy, and I've found cousins who I was able to help with the family tree, getting them back further than they knew.
Hope this helps!