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.
How to read sibling DNA test results. When a DNA test for siblings is conducted, the laboratory will determine the genetic profile of each of the alleged siblings. Based on the type of genetic material exhibited by each person, a sibship index is determined. If the siblingship index is less than 1.00, this indicates non-relatedness.