Below is a brief explanation on how to read/understand genealogy tables. As an example, I use here the table of the principal gods of the Greeks.
As you can see on image 1, the first mentioned are Uranus and Gaea. This means that they are the ancestors or progenitors of the line. The "=" means that they are either married or that they are consorts. The vertical line starting from the "=" and leading (often) to a horizontal line denotes their children.
When there is no vertical line starting from the "=", it means that they have no children.
On the second image (on the right), you will see that the children or offspring of Cronus and Rhea (who are in turn the offspring of Uranus and Gaea) are: Hestia, Pluto, Poseidon, Zeus, Hera, and Demeter.
The third image shows that Zeus fathered Persephone on Demeter. Since Zeus is shown on the same line as Demeter, it makes them brother and sister. You can also see on image 2 that Zeus fathered children on his other sister Hera.