Your people just experienced crusader kings 2 and 3 but in real life. If you know what those games are...heh heh heh ;) If not...heh heh heh ;)

Sadly this has made your people infertile. THEY ARE ALL RELATED! Mothers, fathers are also brothers and sisters but many generations has this happened.

So what do you do? How do you get more people?

Easy, build houses and make your gross people happy with you over 50+ mortality rate and they will invite others to their cult. The more houses, the bigger your cult.

Look at the screenshot, that is what they truly look like but the human brain can't comprehend it so we all see them as human, but really they are mutants in disguise. Now time to grow your manor lord cult! Bring the suckers...I mean...new people into your village by again

build houses
make 50% or higher mortality rate
happy people makes other people want to join in the fun

This is how you play crusader kings 2 and 3, manor lords the same. Except the people in manor lords are -100% infertile after too many years of grossness. Like endgame CK2/CK3 everyone is -100% infertile.