“if you are gay or childless, you cannot care about future generations nor society.”
A logical proposition- if you have no stake in the future, then there is no reason to be concerned.
Aside from the difficulty of conjuring up a more illogical ad hominem style of argument that ignores the tremendous contributions of the childless committed to helping build a better world, on a more positive note, if only parenthood did reliably confer empathy for one’s fellow humans, we would all have better mental health, greater conscience development, and higher intelligence. :)