Genealogy--It's a small world

My dad was curious about his paternal great great grandparents. He wanted to know their names and occupations. My nephew had worked on our family tree, so he was able to tell my dad their names and when they came over to the US from England. Not sure of their occupations although my dad thinks they were farmers. They had six children. I work with a woman at the flower shop and her mother's maiden name and my dad's last name are the same. It turns out that our great grandfathers were brothers, although my dad said that her great grandfather isolated himself from the family. So she and I are third cousins. Even more crazy is that her mother's sister married my mother's brother--her aunt married my uncle and together they had two children. So this woman and I have two first cousins in common.