Peterkin is one of my brick walls. My Great Grandmother (maternal) was Ethel Mae Peterkin 1889-1921. Her father was James Peterkin and his wife was Catherine Exa (yep Exa) Gordon. My Grandmother was named for her and so was my daughter. That's about as far back as I get with solid sources.
Of course all the great group photos I have of the peterkin are not labled. makes me want to cry. I can only ID about 4 in the photo I am attaching