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.
A brother to sister (sibling to sibling DNA Test) works by testing a very large number of different DNA points (known as loci) in each person. Full siblings share a lot more DNA in common than do unrelated persons, and also, half siblings share more DNA in common than unrelated persons, but not as much as full siblings. So this test looks at the amount of DNA sharing and uses DNA statistics to evaluate the amount of DNA sharing to deduce biological relationship.