I Love Genealogy

Some things about genealogy. We are all related if we go back far enough. Considering that the number of one's theoretical ancestors (2 parents, 4 grandparents, 8 great-grandparents, etc) doubles with every earlier generation, and there is a new generation about every 25 years (in pre-modern times), going back as far as 1200 A.D. you get a number of ancestors theoretically alive at that time larger than what we estimate to have been the entire population of western and central Europe. The computer models demonstrate that all of us (including most Black people who have white ancestors) are descended from everyone who was alive in most of Europe at that time and who still has descendants. (Many people never have children or their descendant lines later die out.) So, Heart, it gives me great pleasure to declare that you and I are cousins--we just don't know how far back the connection is. And, I am a 6th cousin twice removed of the late Duchess of Windsor because on of my ancestral lines comes out of colonial Baltimore where Wallace Warfield Simpson grew up.
In the American South, it was common, especially in upper class families for first cousins to marry. This was also often true in the British royal family. (I think it was George II's parents who were first cousins.) There are no ill-effects except that certain kinds of rare diseases are more likely to manifest themselves if the father and mother are related.
Having a lot of DNA matches in Australia probably means you descend from north European peoples some of whose descendants went to America and some to Australia. If these things interest you, read any of the popular books written by Bryan Sykes.
As for my own background, it is British (English, Scottish, and Welsh) and German (mostly north German).