I want to take a short detour from DNA and genealogy to discuss what is simple to most people, but surprisingly less so for me: my name.
My original birth certificate would ordinarily have my birth name, and the names of my biological parents. As an adoptee, I am not entitled to it (presumably for these reasons). As a result, the birth certificate I do have is re-issued with my adopted name. This is well enough for all the identification reasons someone would need their birth certificate for, but it's not particularly helpful for my search.
When I took my birth certificate to get my Maryland driver's license some years ago, the DMV clerk pointed out to me that my birth certificate had no middle name. Now, ever since I was adopted, I have used James as a middle name. It's one my birth parents gave me. Nonetheless, it's not on my birth certificate, and (because of that) it's not on my driver's license. But it is on my passport (which, presumably, I needed my birth certificate or driver's license to obtain).
That's a long-winded way of wondering: I have been using a middle name for nearly 4 decades. What is my name? Do I even have a legal middle name?
I took a test this morning and had to register without my middle name because the test registration had to match my driver's license. Apparently, the force of using my given middle name for 40 years is not good enough for some things.
Whether I have a middle name or not doesn't seem to have ever caused me any problems. If I need a middle name, I have my passport. Otherwise, I don't appear to actually have one. Nonetheless, one would think that your name is fundamental to who you are. For me? Not so much, apparently.