Uncle Phil

Mum knows all too well her younger brother is fucking me. She should do, she walked in on me sucking his dick in the kitchen a few weeks ago.
He's living with us now. And every morning he fucks me in the shower, or if mum goes to work early, we fuck mainly in my bedroom.
There is no dad, so mum decided late last year he could move in with us after his place got ruined in a flood.
Within weeks I was giving him head as I'd caught him wanking to porn on his phone.
There was no reluctance either, and once he knew i wanted him we began having sex.
Mum turns a blind eye to her brother fucking me, but since I can't have children, she allows us to enjoy one another.
However this isn't why I'm confessions.
Only the other week, I found out off a really close friend of my mums, when they were teenagers, Phil and my mum were lovers.
Apparently they would have sex at every opportunity and even though they've never had a paternity test, I think I've worked it out, my uncle is in fact, my father.
The real reason I think mum wanted him to live with us.
Neither of them know I know. But now i can't figure out if she does indeed know he's my dad, why does she let allow him to fuck me.
And knowing all this I still love him giving me the sex I adore with him.