I understand, but truth should not be our enemy.
Certain truths within these laws do exist whether we recognize them or not.
That is not the case. It was considered ... wickedness.
"Thou shalt not uncover the nakedness of a woman and her daughter, neither shalt thou take her son's daughter, or her daughter's daughter, to uncover her nakedness; for they are her near kinswomen: it is wickedness" (Leviticus 18:17).
For you can actually defile yourself with these things.
"Defile not ye yourselves in any of these things: for in all these the nations are defiled which I cast out before you:" (Leviticus 18:20).
In fact, I believe certain (next of kin laws and not all of them) like sleeping with one's mother was always forbidden. How so?
For one, our nature built within us tell us this is wrong. Two, we see that this is what wrongfully happened between Noah's wife and his son, Ham. For it is why Noah cursed the offspring of Ham (i.e. his son, Canaan). For the words "uncover the nakedness of a particular person" was in reference to their spouse.
Leviticus 18:7 says,
"The nakedness of thy father's wife shalt thou not uncover: it is thy father's nakedness."
So we have:
Thy father's wife = thy father's nakedness.
So when Genesis 9:22 says,
"And Ham, the father of Canaan, saw the nakedness of his father, "
The nakedness of his father (Noah) was Noah's wife.
It is talking about Noah's wife.
This is done for the obvious reason so as not to humilate her within the Scriptures.
Anyways, in light of this, I now need to say that some of God's laws on "not sleeping with kin" are "Eternal Moral Laws." while others were temporal (and came about during the time of Moses).
I see it as a means of God desiring to fill the Earth.
"Be fruitful, and multiply, and replenish the earth." (Genesis 9:1).
In fact, when they didn't do that, and they just stayed in one place, God confounded their language and scattered them abroad.
"....the LORD scatter them abroad upon the face of all the earth.." (Genesis 11:9).
God wanted to populate the planet Earth with man and for him to have dominion over it.
For it was a command given to Adam and Eve.
"And God blessed them, and God said unto them, Be fruitful, and multiply, and replenish the earth, and subdue it: and have dominion over the fish of the sea, and over the fowl of the air, and over every living thing that moveth upon the earth." (Genesis 1:28).
In other words, God naturally rules;
And man was created in God's image.
So it has to do with God wanting man to have rule over the Earth.
Yet, families existed since after Adam, though.
And geneologies were kept even back then.
Abraham before the Law was promised the inheritance of the Promised Land;
Abraham was also promised that his descendants would be as the stars of the sky.
...