As discussed in the previous blog, parents pass down a random half of their DNA to their children. Whether that random half has more DNA from a grandfather or grandmother is also random. So even though children get 49-51% of their DNA from each parent, the amount of DNA they inherit from each grandparent can be markedly different than 25%. If your grandparents get testy about this, remind them it’s not a competition!

Gene Heritage’s Grandchild Report calculates what percentage of DNA an individual inherited from each grandparent. In this example Grandchild Report, Jean Mendel inherited 30% of his DNA from his paternal grandmother Greta and only 19% from his paternal grandfather Gregorious. As you can see from the report’s donut chart, even though we inherit on average about 25% of our DNA from each grandparent, the actual percentages can be strikingly different.