Each of us has half our genes in common with our siblings, but we have only one-eighth of our genes in common with our first cousins, only 1/16th with our first cousins once removed and only 1/32nd with our second cousins. Translated to percentages, that means we have just more than three percent of our genes in common with our second cousins. And the percentages get exponentially smaller the further and further we go through the numbers and the removes.---If you are confused at family reunions or as Dennis Norman calls them family rebellions, then you are not alone. The definition of full cousin is the child of one's aunt or uncle. A person's second cousin is the child of one of his parents' first cousins. A person's third cousin is the child of one of his parents' second cousins. A first cousin once removed is the child of one's first cousin. What helped me understand it a little better is when it was put this way… “First cousins share a grandparent, second cousins share a great-grandparent, third cousins share a great-great-grandparent, and so on. The degree of cousin-hood ("first," "second," etc.) denotes the number of generations between two cousins and their nearest common ancestor. The term "removed" refers to the number of generations separating the cousins themselves. So your first cousin once removed is the child (or parent) of your first cousin. Your second cousin once removed is the child (or parent) of your second cousin. And your first cousin twice removed is the grandchild (or grandparent) of your first cousin.Whether you understand it or not, the fact is, genetic connections fall away very quickly as we look farther sideways on our family tree. In fact, those connections decay geometrically.