There doesn't have to be any incest and there won't be any. I'd like to remind you again that Lynette didn't return to Neil until 3, maybe 5 or even 7 days later. What if Lynette got pregnant during that time and not by Neil?
It is even implied that Neil could not be the MC's biological father. Right at the beginning we read that family doesn't necessarily have to be blood relatives. Luis said to the MC so that he would become more and more dissimilar to his father. It is also implied that Neil could have another child or children. The thing with the condoms doesn't just point to STDs, but also to unwanted pregnancy. In the diary we read that Neil reminds Luis of a woman from a year ago. So what would happen if Patrick wasn't the father of Maya and/or Derek? Patrick once said to Maya so that she wouldn't be the daughter he wanted.
One should also remember that Lynette and Neil weren't married. So if the MC is not Neil's biological son, but Maya and Derek are Neil's children, Maya, Derek and the MC would still not be siblings. I would also like to remind you of what Derek said to the MC. "My brother will be my brother-in-law."
Lynette's diary alone can provide complete information about who the MC's biological father is. The timing of the diary's appearance is strange. Why? Only after Rich has a death in the family (EP3) does the MC get the diary in EP6. Let's imagine a scenario. Someone dies, a safe is opened and inside is a diary that has been locked away for 19 years. The diary is read and reveals to the reader who the MC's biological father is. Only when this is finally clarified will the MC's family situation be clarified.
