Whether that’s relevant depends on your values in the first place: are you a harm-based consequentialist?
As it happens, yesterday I took a survey (“Argument Evaluations”) on YourMorals.org which asked exactly that question (“how relevant is the argument that ‘children raised by gay couples may be harmed’ to the morality of gay marriage”) and you will be unsurprised to look at the results and see that people differ on what arguments are relevant to the morality of gay marriage:
Whether that’s relevant depends on your values in the first place: are you a harm-based consequentialist?
As it happens, yesterday I took a survey (“Argument Evaluations”) on YourMorals.org which asked exactly that question (“how relevant is the argument that ‘children raised by gay couples may be harmed’ to the morality of gay marriage”) and you will be unsurprised to look at the results and see that people differ on what arguments are relevant to the morality of gay marriage:
(Green is me.)