Same-sex unions are recorded in the history of a number of cultures, but marriage or similarly formalized same-sex unions were rare or nonexistent in other cultures.
Using this measure, siblings are actually 99.95% the same. The 50% refers more to the amount of DNA we get from mom and the amount we get from dad. So we are more similar to our relatives than we are to a mouse. Let's explore in a bit more detail what the 99.95% and the 50% numbers mean.
Still Siblings Even with No Matches. A DNA test looks at certain parts of the DNA called markers. Different markers are given different numbers to distinguish them from each other. (Click here to learn why they are numbers.) So, a certain marker called THO1 might come in 6, 7, 8, 9.3, or a few other possible numbers.