Questions about DNA and genes?

Will the 2 children with the same parents have exactly the same results?

Unless they are "identical," no. They will not even have the same chromosomes and that's how you can distinguish the brothers or sisters. Full siblings will share mitochondrial DNA and * around * 23 chromosomes, which means that each has approximately 23 chromosomes that their siblings do not have.

There is no genetics by nationality, ethnicity or place of birth / residence. All there are are mutations in their 47 DNA packages (23 chromosomes from either parent) and DNA databases in which you can find the most similar packages to yours. The proof will not find his great grandfather in the nineteenth century, but he may find that his 4th cousin is removed twice if the same test was done in the same company