The GrandTree allows you to trace the inheritance of genes from grandparent to grandchild. You can trace overall genetic similarity, genes associated with the traits in the list, or a gene or group of genes you enter yourself. To do this, follow these steps:
1. Select a trait from the list.
2. Fill in the tree by selecting a grandchild, then add available parents and grandparents.
3. Review the percentages shown for the selected trait:
If you have placed a grandparent on the paternal side, the tool will calculate how many genes in the selected group passed to the grandchild from his/her paternal grandfather and how many passed from his/her paternal grandmother. The same is true if you place a grandparent on the maternal side.
You only need one grandparent to trace inheritance down either the paternal or maternal side, but to trace inheritance down both sides, you will need at least one grandparent on each side.
Note that adding more grandparents usually improves our estimates, so while the GrandTree works with just one grandparent, adding more could improve the accuracy of the estimates.
Using GrandTree without grandparents/grandchildren
Even without genetic data, we already know that everyone inherits 50% of their DNA from their father and 50% from their mother. The process of recombination, in which each parent's chromosomes shuffle before being passed on to a child, means a person does not always inherit exactly 25% of his or her DNA from each grandparent.
The Family Traits GrandTree is designed to calculate how much DNA a grandchild inherited from each grandparent - and also which genes came from whom. Without data for your grandparents or grandchildren, though, we cannot perform these calculations.
The GrandTree relies on you to correctly place yourself and your relatives on the tree. It will still attempt to calculate inheritance even when the placement is incorrect, but results are valid only for correctly placed relatives.