It is though the strong taboo against cousin marriage is relavtively recent and kind of weird and supported by incorrect beliefs that you'll definitely have flipper babies instead of any kind of analysis of power disparities or family dynamics.
From a genetics and general health perspective having babies with a first cousin creates a trivial risk unless you're both carrying genes for some serious condition. Condemning cousin marriage bc genetics is not valid and is probably left over gene hygeine nonesense from the bad old days of eugenics.
If you have a social critique of cousin marriage i am 100% on board to hear it, but if you bring up genetics I will point at you and laugh.
Sincerely; i'm an anthropologist and marrying your cousin is weird in our cultural moment but has been entirely normal in many places in the past and doesn't cause your babies to be born with tentacles and fangs.