I'm wondering whether there are any cases in linguistics (or related fields like Cognitive Sciences) where this debate is being used for harm?
The subject of nature vs nurture is a hot debate and is very divisive in many scientific and non-scientific communities.
Where there is prejudice, there can be harm on both sides of the debate
In cognitive sciences, I can think of 2 examples straight away.
Good and evil inborn or developed?
The debate on whether good and evil is inborn or down to upbringing or other environmental issues has been raging for decades. The research by Philip Zimbardo, Stanley Milgram, Soloman Asch et al. shows that. It can also be seen to be harmful on both sides or the debate.
Sexual abuse of a child is an evil that most people want to eradicate. This in turn has led to a fight against paedophilia, hebephilia etc. when it is debated that paedophilia etc. are sexual orientations which may not lead to sexual abuse of a child. After all, male rape of men and boys can have nothing to do with homosexual orientation (one example of research outcomes)
If it is inborn
If it's inborn, what do you do about the evil people born that way? They can't help it after all. Do you put an extremely close 24/7/365 watch on them in order to step on the moment they are about to do something evil?
Maybe you look to eugenics to eliminate the problem by aborting future pregnancies which could lead to an evil person being born. But that is not fair on the unborn child as it may not be 100% accurate and the child could turn out to be a Mother Teresa or Mahatma Gandhi incarnate.
Maybe you could sterilise evil people so the gene pool for evil people is weakened. But that is unfair on the potential mother of a child who again, could turn out to be another Mother Teresa or Mahatma Gandhi.
If it is nurture
Do you put aside your indifference toward evil people, admonish those who caused it (mothers, fathers, school teachers, politicians, influences on social media...) and support the evildoers toward going the other way, or do you punush both and leave the admonishment to correct their ways? After all, it costs a lot of money to imprison an individual and the finances are finite.
Homosexuality inborn or influenced?
If inborn (which is where science has swung toward)
There has been, and continues to be, incidents of fear of the unknown where straight people worry there will be issues from homosexual people coming on to or attacking heterosexual people. So, this fear induces violence toward them.
There has been a search for "the gay gene" and that has caused controversy as that has good and bad implications and scientists have sought to "kill" a particular test for homosexuality. There have been calls for eugenics to step in to eliminate "the abomination". Do we try to remove homosexuality through genetics? That is actually a debate in some circles.
Do we prevent gay men from donating sperm? Do we prevent them from fathering a child through surrogacy? Do we use conversion therapy to stop them acting on their urges? Do we try to develop brain implants to "cure" it?... The list can go on. After all,
Homosexuality has been [attempted to be] treated with lobotomies, chemical castration, electrical shocks and nausea-inducing drugs as well as psychotherapy.
If there are environmental influences
Again, fear of the unknown steps in. Can a straight person be made to be gay by another gay person? Should we prevent gay people socialising with heterosexual people? Should we just beat it out of them?
Should we perform lobotomies, chemical castration, electrical shocks and nausea-inducing drugs as well as psychotherapy?