I doubt that letting gay couples to marry each other would disable the continuation of human race.
Few abnormal acts would.
How? You do know that there was homosexuality in the past like in the Roman Empire and Ancient Greece? Kind of we all have survived and nothing has changed. The population of the world has even grown.
Yes, I'm well aware of history. Just because an activity has a long history doesn't make it normal. I'm sure you can think of examples.
