One of the more personally disheartening divides in modern Celtic paganism is over the matter of gay rights. One individual who identifies as Gaelic Traditionalist (I'm led to believe some GTs would rather he stop making them look stupid, thus the dodge language) recently snarked that "the bridge crew of the USS CR" hauled its personal politics into Celtic religion along with them. I put it as "them" because I wasn't there for the start of it. I just happen to agree wholeheartedly with keeping Celtic reconstructionism a safe place to be queer.
In a large respect, the pro-gay stance of CR/senistrognata is indeed an import with no easy proof our ancestors would have felt comfortable about it. Same-sex marriage was impossible under brehon law, albeit for heavily biological reasons. Marriage and children were linked to where some of the lesser degrees of it were designed to protect the interests of both the mother and the offspring gotten by a one-night stand or a rape. Brehon law is mostly silent on the topic of homosexuality. The modern concept of a queer identity was non-existent then. But the fact some people had same-sex relations was well known. One of the valid grounds for divorce under brehon law was discovering your spouse was only interested in having sex with members of their own gender. My readings in early Irish Christian penitentials has led me to discover very specific descriptions of same-sex activities that were frowned upon by the Church, so the behavior was religiously proscribed under that tradition. But the pre-Christian attitude in Ireland is not noted.
Greek writings about the behavior of Gaulish soldiers may shed some light, though. Those men had no problem with at least situational homosexuality with little respect for military rank in their choice of partners. We're not talking Theban pair-bonding, which was blatantly pederastic. The writer made it sound as if the soldiers' idea of a good night off would be fit for a Castro District porn store shelf. Was it just because the women weren't there? Quite possibly. But that to me indicates a more flexible attitude toward sexual behavior than that of modern times. Your average American male would see extended time away from women as a reason to learn new variations on what his dominant hand can do. I've also seen a translation of Roman graffiti in which one man declared he was abandoning all attempts at dating women in favor of men. No identity labels were involved, just a statement of behavior.
It would be easy to romanticize the situation based on scanty evidence. At the same time, I am hard put to see where refusing to treat queers as equals is inherently more Celtic than embracing the concept. And if it's more Celtic to sneer at the notion of supporting rights for all regardless of sexual orientation or identity, then I think I'd rather be American for that aspect of my beliefs. Self-hatred is quite definitely not one of the Celtic virtues, and I know what I'd rather be Gaelically incorrect about.