It's amazing what we can do with genetic manipulation. We can see how closely two organisms are related genetically, without having to rely on physical similarities, which can be quite misleading. We can express proteins from one living thing and express it in another, even in specific tissues. For example, fish can make protein X on the linings of their gills. It is possible to have protein X be expressed in just the brain of a mouse.
Genetics itself determines everything, from our hair color, to the tameness of dogs versus wolves, to the probability of us having cancer, or children with congenital defects. By manipulating genetic material, we can alter what makes us us. I think that is absolutely remarkable, and I hope you do, too.