No, it likely won't, due to inbreeding and polygyny. Your grandparents and great-grandparents are probably all unique, but go back enough generations, and your family tree starts intersecting itself.
Simple example with polygynist great-grandparents and first cousin parents.
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Because his great-grandparents were polygynists, and his parents were first cousins, he has four great-grandmothers and two great-grandfathers. I used first cousins solely due to space constraints. Something similar could obviously be constructed with more intervening generations between the cousins.
Second cousin marriage was fairly common in the past, first cousin marriage wasn't unheard of, and nobody even bothered to track third and fourth cousins. In little medieval villages where nobody had ever gone more than 100 miles from home, you're going to have a lot of intersections.