Actually, it does. Facts can’t be copyrighted. If I find facts on the public internet, it’s legal to sell and use in most jurisdictions around the world.
If I don’t want the world to see material, I don’t give it away for free to everyone.
Yes that's true, but copyright is not the only restriction about the use of data you find online. There's trademark and privacy to consider. I don't think either thing is likely to apply to dead people :)
Trademark also doesn’t apply to facts. And if data is published on the open internet then privacy is most likely not an issue. The genealogy is already published in the open.
So I don’t think those elements are relevant to the conversation without more context.
If I don’t want the world to see material, I don’t give it away for free to everyone.