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.
After all, they both got half their DNA from mom and half from dad. But because of how DNA is passed on, it is possible for two siblings to have some big differences in their ancestry at the DNA level. Culturally they may each say they are â1/8th Cherokeeâ but at the DNA level, one may have no Cherokee DNA at all. So yes, it is definitely possible for two siblings to get pretty different ancestry results from a DNA test. Even when they share the same parents.