The popularization of mother-son incest in hentai has polarizing opinions to say the least. From high level traditionalists to low level students the opinions vary in range from congratulatory to sickening. Even in the late 1970’s early 80’s the situation and popular reporting of the issue was in a polarizing state.

https://www.reddit.com/r/anime/comments/3yht7f/motherson_relationships_anime_history/