She took a DNA test and made the results public. She knew how that made her look and did it anyway. There was no legal requirement for her to do so. And then she actually apologized.
All of the above is what separates her from being the horrendously despicable human who now serves as POTUS.
Trump would have persisted in the lie, screamed fake news, never had the test, certainly never would have made it public, and would have sacrificed his children before apologizing.
See his whole tax return body of lies.