There are many supporting statement in Hume's writings to support the point that moral facts are inherent in human nature.
Here is one significant one;
As I had stated, it was unfortunate for Hume that during his time there was no knowledge of human nature in terms of the anatomy of the brain, neurosciences, genetics, molecular biology, genomics and the likes.Hume in Treatise of Human Nature wrote:
Take any action allow'd to be vicious: Willful murder, for instance.
Examine it in all lights, and see if you can find that matter of fact, or real existence, which you call vice.
In whichever way you take it, you find only certain passions, motives, volitions and thoughts.
There is no other matter of fact in the case.
The vice entirely escapes you, as long as you consider the object.
You can never find it, till you turn your reflexion into your own breast, and find a sentiment of disapprobation, which arises in you, towards this action.
Here is a matter of fact; but ’tis the object of feeling, not of reason.
It lies in yourself, not in the object. 1
Treatise of Human Nature, Bk III. Pt1. s1, p. 469
If Hume have had knowledge of the above, I am sure he would have adopted our current advance knowledge of the above to support his matter-of-fact underlying the feeling of the moral propensity - that lies in the human self, i.e. human nature.
The above is food for further thought by those Moral Fact Deniers, who cling to Hume's 'no ought from is' from the obvious but are ignorant of the deeper issues claimed by Hume re human nature in his Treatise of Human Nature, Bk III. Pt1. s1, p. 469.
Views?