Same-sex marriage, also known as gay marriage, is marriage between people of the same sex, either as a secular civil ceremony or in a religious setting. 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.
DNA between siblings are similar if you share the same biological parents. The genetic information you gain comes from both of your parents, and are a result of fertilization of 2 haploid cells fusing to form a zygote that has a diploid number of chromosomes.
Even though Stan and Pierce do not have the same copies of each of the markers, they both always have one marker from their mom and one marker from their dad. Which means they are almost certainly brothers. So there you have it. With simple DNA tests, siblings can match at any number of markers. They can match at all, none, or somewhere in between. This has nothing to do with how related they actually are at the DNA level. Siblings are about 50% related.