31 Now the firstborn said to the younger, "Our father is old, and there is no man on the earth to come in to us as is the custom of all the earth.
32 Come, let us make our father drink wine, and we will lie with him, that we may preserve the lineage of our father."
33 So they made their father drink wine that night. And the firstborn went in and lay with her father, and he did not know when she lay down or when she arose.
34 It happened on the next day that the firstborn said to the younger, "Indeed I lay with my father last night; let us make him drink wine tonight also, and you go in and lie with him, that we may preserve the lineage of our father."
even though it was to preserve the lineage of their father, was that something, you know, okay at the time? was there no problem or thinking twice over this, that it's their father, or was it just long ago, if you are doing this type of thing for an important purpose other than to satisfy your desire, it was alright?