No, it hasn't happened on multiple occasions. It happened one time thousands of years ago in one region of the Earth. I must remind you that the industrial revolution and the social ills it brought happened more recently. We aren't talking about the same thing.

What? Researchers have absolutely used data (or consent for one procedure) specifically to excuse eugenics, nonconsensual experimentation, and policy decisions that keep "undesirable" folks out. Science has a long and continued history of this. I'm not sure what you are even suggesting ...

Examples of things like the Tuskegee Experiments, the North Carolina Eugenics Board, hell, we're less than a decade past when hundreds of women were sterilized because they were thought to be "unfit" because of their prison sentences and race.

Nazis tried to use pseudoscience to exterminate everyone that didn't have an ancestry lineage to the sunken city of Atlantis. You are spouting a ridiculous myth, eugenics has never been scientific, it's all about trauma and lies.

Since you asked, search for Ayurveda. Vata, pitta, and kapha describe these brain types that have been a permanent staple of society since we left Africa. Ayurvedic societies were able to be efficacious by ensuring everyone has a role in social life by understanding what makes us different and using it for everyone's benefit.

Oh course eugenics is trauma and lies.

But it's been popular and studied by people who called themselves scientists many times. You and I would agree they aren't scientists, but the public sure think they are at times.