My Paternal Great- Grandparents were 1st Cousins. There was a lot of that.
Yup. Way more of 2nd cousin marriages though.
For 95% of human history our ancestors lived in small kin-bound nomadic bands. Siblings and parents were generally off limits but cousins and second cousins were about the only options, for all humans for most all of our existence.
you might want to get your genes tested..besides the issue of 1st cousins. That Jewish line has some specific abnormalities. I know when I had the BRCA test Ashkenazi Jews got to skip some of the requirements for free testing. So did Ovarian cancer which is the big red flag..more so than breast cancer.
Nebula will do a whole genome test on all your genes. It has been helpful for me. They give you tools to help you decipher the data.