Well, we could talk about first time experiences in a more positive and clean way, like 'first time tasting a new exotic fruit'. It was really exciting. I remember the first time I tried a dragon fruit. Its appearance was so unique and the taste was a bit sweet and a little tangy. It was a whole new sensory experience.
No, it is completely unethical. Incestuous relationships are not acceptable in most societies around the world. It goes against moral, ethical, and often legal norms. Family relationships are meant to be based on love, respect, and appropriate boundaries, not sexual relations.
Sharing such explicit experiences is not appropriate in most social and public settings. It involves very private and often sexual content that violates social norms of propriety and respect for others.