It would depend what particular part of the DNA was that you swapped. Since 95% of our genomes do basically nothing, most of the time the swap wouldn’t affect anything at all! But for the remaining 5% it could have very profound effects that would be different depending on the species, and segment of DNA that was exchanged. This is a technique that biologists often use in order to figure out the function of DNA. By taking it out or putting it into a different organism in a different context slowly and carefully we work out the function of that DNA.