In our family we believe that my great grandparents on my paternal grandmother's side were cousins.
I have a second cousin on FTDNA from this line . Her maternal grandfather and my paternal grandmother
were siblings. we share over 309cM's
FTDNA gave a relationship range of first-third cousin and suggested a second cousin relationship. 309 is high for second cousin, so I' m not sure how they arrived at that.