Hello.
I did a 23andme test. It got me thinking about my ancestry which is just English and Polish. I was wondering what are the chances that I had an ancestir who picked up arms and fought? And by ancestors I mean before guns.
While this older answer of mine isn't quite about what you ask (and could use some polish, tbh... 6 years is a lifetime online!) it does get to the heart of your question nevertheless in its focus on common descent and how many ancestors you have going back 500+ years. It is not only safe to assume you had many military persons in your family tree during the medieval era, but going back to the early medieval period, anyone alive in Europe who had descendents is probably in your family tree.