When a tribe depends on children being born for its survival, do you believe that gay (non-child producing) relationships should betreated the same way as child-producing ones?
That completely misinterprets the whole of human evolutionary behaviour and society.
Human societies aren't set up to generate the most number of babies - rather humans have very few babies, in comparison to many other species - their societies are developed to provide the best opportunity that those babies survive through to adulthood, particularly during the early stages when they are extremely vulnerable and need both protection and later to learn from the rest of that society.
There is an evolutionary theory (which is rather convincing) that sexuality is determined in utero and is linked to earlier births (first born children being less likely to be gay). Given that gay people may not have children, but may support the upbringing of other children, this is entirely consistent with benefit to the overall human society and evolutionary drivers (the children of the earlier born being more likely to survive to adulthood).
But in an ethical sense the answer to the question 'do you believe that gay (non-child producing) relationships should be treated the same way as child-producing ones?' - absolutely, to think otherwise is abhorrent. Hope do you think that infertile people (non-child producing) should somehow not be treated the same in relationships as fertile couples?