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.
SIBLING FULL TEST - US$ 395. 1  If you need to test a brother and sister for the same father, then you will need to do a full sibling DNA test. 2  Siblings share more DNA than do unrelated persons. 3  Order the kit (paperwork, swabs and instructions), or buy the test now.