In SWMBO's family her grandparents' generation had large families over long periods.
Glossary:
SWIMBO = "She Who Must Be Obeyed"
(Don't want Dave any more confused than he is already)
I have a will dated 1822. Testator was brother-in-law of my 4xGGF. They were also cousins of some degree and shared a surname. Newspaper announcement of the death in 1822 referred to the deceased as brother of my 4xGGF ( owner of a prominent local business). I was confused for a while, since my 4xGGF had a brother with the same name as the man who died in 1822 but my ancestor's brother died in infancy. Moreover, the testator had a brother with same name as my 4xGGF.
To complicate matters further, the testator and 4xGGF were related by marriage twice over. Testator married 4xGGF's sister. A few years later 4xGGF married testator's sister. I'm not sure if an executor of the will was testator's brother, nephew or grandson, as all had the same name.
As if this wasn't complex enough, a daughter of 4xGGF married the great-grandson of a man who was probably great-uncle of 4xGGF. I calculated that married couple to have been 3rd cousins to each other. They may have been related in other ways too. It was probably simpler to call everyone cousin.