If we accept that events in life can scar or even just affect you for life (as this article claims) then why stop there? These people have children. Do you think that habits that form out of trauma, housing insecurity, food insecurity or were in fear of their lives don't subconciously impact their children?
We don't even have to imagine that. We have physical evidence that the conditions a woman faces can impact her grandchildren [1]. Remember that a cis-woman is born all the ova she'll have so pregnancy conditions can affect grandchildren.
But even if you ignore the physical, you'll find cultural and psychological effects on children from people who, say, fled a war zone or survived the Holocaust or whatever.
If you accept all that you've then accepted that generational trauma is real (which it is).
So what do you think that slavery did to people long after chattel slavery (officially) ended?
[1]: https://www.science.org/content/article/moms-environment-dur...