I Dunno About Those Doanes

Thanks to my cousin, whom I met this summer at our family reunion, I have a few more generations to add to my family tree and a lot more researching to keep me busy, but the more I search, the more the same surname keeps popping up, Doane. I am researching my 2nd great-grandmother's family, the ancestors of Mary Elizabeth Robbins, who married Allen Cark Doan in Welland, Ontario in 1876.
Her father, Caleb Robbins was born in Gainsborough, Pelham Twp., Ontario in 1837 and married Catherine Pattison, daughter of John Wright Pattison and Catherine Rinker, in Welland in 1858. Caleb was the son of Nathaniel Robbins and Hannah Doane Nickerson. Hannah Doane Nickerson's parents were Elkanna Nickerson and Hannah Doane. Hannah Doane was the daughter of Benjamin Doane and Hannah Smalley.
My cousin's father told her that the males of the Doane family had a custom of marrying the females of the next generation. I don't know if this is true, but here are more than the average number of Doane intermarriages just in my direct line:
My parents are one example, they were first cousins once removed.
My 2nd great-grandparents, Allen C. Doan and Mary E. Robbins.
My 2nd and 3rd great-grandparents, Linus C. Doan and Hannah Maude Doan (my parents' common ancestor).
My 3rd and 4th great-grandparents, Isaac Doan and Polly Charlotte Doan.

No wonder I can't walk and chew gum at the same time! ;-)