Is it just me, or is it kinda weird that it seems that according to the bible it used to be ok to marry and have kids with your siblings?

I just seen a video that said Adam and Eve had sons and daughters who married each other and had kids. But that it was ok in those days since the human genome was free from any type of mutation so the problems that we would see today from having children with your siblings wouldn't have happened back than. Idk still sounds gross and weird to me