This manga is one of a kind. The drama is topnotch. However, they grew up together, how are they attracted to each other? Since they were raised as brother and sister, they would likely to have been desensitized of romantic feelings. They are also blood related, so any kids they have will likely suffer from some genetic issues. Not guaranteed but highly likely.
And I hope Joel sticks with that decision. The author seems aware that Chase is too young to date Joel. I hope romance will not take precedence over pedophilia.
this is not pedophilia, but the author is lamp shading the situation. Chase and Joel getting together would be morally wrong given how it would be hypocritical of Joel to become romantically involved with a young man his son's age, despite being possibly homophobic, angry at the math teach sexually using Chase and other students, and lastly never providing his own son Jesse with any form of affection. Yet, the author still wants us to desire Chase and Joel end up together out of love fully recognizing how wrong and unethical their relationship would be. It's the true love will overcome excuse in obstacle ridden romance plots.
Sadly I do not have faith in Joel's character to do the right thing. It was so easy for him to drop everything to go running to Chase. He didn't even think about it. He immediately left and lied about going to work. He even used his badge and threatened a case of statutory rape (which apparently does not apply to him). At this point, Chase has him dancing in the palm of his hands.
From my research, pedophlia cases seem to cover upto 11/14/16 years of age. Either way it could be considered sexual defilement of a minor. But I do agree with you that the author is lamp-shading. They seem to highlight all the possible scenario of men other than Joel as wrong, but keep Joel's romantic interest on a pedestal.
That feeling is usually the worst in the world. Poor baby. Kudos to the Author, the writing came through so well.