@bdjwwata
The dude literally birthed his daugher from his dantian.
Immortals can do impossible things, like changing their appearance to that of animals, change their gender on a whim,etc..
His wife wasn't raped by him, but rather "her thougth/essence/etc" was the mold to form the child, hence why he called her "their daughter". It was confirmed by DNA tests that they have no blood-relations (because the girl is literally a pure-immortal born from an immortal's dantian...).
//Are you maybe thinking about Immortal Nanny Daddy / Immortal Fairy Daddy?
In that manhua, the MC really laid the female protag, but the 'wife' was poisoned by an aphrodisiac, and according to "chinese medicine", if someone is suffering from an aphrodisiac poison, the only cure is dique.