The Specific is Covered in the More General
Leviticus 18:17a states (NKJV):
You shall not uncover the nakedness of a woman and her daughter
If a man has a daughter, he certainly (at least in that time before in vitro fertilization, etc.) has experienced sexual relations with the "woman" who is the mother of both "her daughter" and his daughter. Now 18:17a would generally include stepdaughters as well, but that general statement also includes the specific case you are inquiring about of one's own daughter. So there was no need to specify "one's own"your daughter," when this more general statement already explicitly included the instance of one's own daughter with a woman.
So while many commentators have spent time discussing a supposed "gap" in Leviticus 18 because one's own daughter was not singled out for mention, and even gone further to try to figure out "why the gap is there in the first place,"1
a singling out is not needed because 18:17 covers her case. That is:
- "A woman" explicitly covers any woman one might have had sexual relations with (wife, concubine, prostitute)
- "her daughter" explicitly covers any female born from that woman who [the woman, not the daughter] one has had sexual relations with
There is no explicit exception clause, nor reason to infer, that "except one's own daughter that is from your sexual relations with 'a woman.'" All B of A are included, that is, all daughters of a woman whom a man has uncovered the nakedness of are off limits.
This statement, made so, expands the prohibition to be more than merely one's own daughter, but its wording in no way indicates one should exclude one's own daughter from the set of daughters that are off limits from a woman he has had sexual relations with. And the reverse implication is that a woman's mother is off limits as well (in the case of the sexual relations being with the daughter). The point is that a man had to choose one, not both, to interact with sexually. Clearly, if the man fathered the daughter, the choice was to interact with her mother.
NOTES
1
Jonathan R. Ziskind, "The Missing Daughter in Leviticus XVIII," Vetus Testamentum 46:1 (Jan 1996), 126.