How much DNA you will have identical to my aunt?

Answer 1

Statistically, you are likely to share 25% of your DNA with your aunt. The precise division of genes in mitosis is fairly random; your match could be anywhere from very low number to 50%. Or greater, depending on how close your other relatives are.

Assume, for example, that your mother and your aunt are sisters. (The math would work almost the same way if your aunt is your father's sister.) The genetic match could be 100%, if your mother and aunt are identical twins, to something close to zero. Statistically, they are likely to share somewhere near 50% of their DNA. I assume that your parents are entirely unrelated, which probably is not perfectly true, as we all ARE "cousins under the skin", if you go back far enough. So the average of 50% from one parent and zero percent from the other indicates that statistically, you are probably somewhere near 25% related to your aunt.

If your parents come from fairly similar ancestral stock - for example, both Irish or both Japanese, or even just both European or both African - then the percentage of common DNA would be some unknown value higher. It's certain that before the industrial era of cheap transportation, your great-great-grandfather almost certainly married his distant cousin. And maybe not all that distant, depending on the size of their village!

If your aunt is an "in-law" relative - for example, if your aunt is your father's brother's wife - then the percentage of match could be quite low. Again, this would depend on how far back you share a common ancestor.

Answer 2

You will share about 25% of your DNA with your aunt, as she is a first-degree relative. This percentage represents the amount of genetic material that you both inherited from a common ancestor, in this case, one of your parents.