"The evidence shows that the movement of marriage away from a gendered institution and toward an institution free from state-mandated gender roles reflects an evolution in the understanding of gender rather than a change in marriage.
The evidence did not show any historical purpose for excluding same-sex couples from marriage, as states have never required spouses to have an ability or willingness to procreate in order to marry. FF 21. Rather, the exclusion exists as an artifact of a time when the genders were seen as having distinct roles in society and in marriage. That time has passed."
https://ecf.cand.uscourts.gov/cand/09cv2292/