Being a terminal branch on the family tree might not feel very noble. But on a planet this size, infested with over 6,000,000,000 humans, noble may be precisely what being grandchildless is.
Will mankind be helped or harmed by this deprivation? Who cares?
In 1951(!) C.M. Kornbluth wrote a story, frequently anthologized, positing a man journeying forward in time. When he gets there, he finds the intelligent people now in the past had voluntarily limited their reproduction. The less intelligent, neither understanding nor caring about the idea of overpopulation, hadn't.

Hence the title, "The Marching Morons." imageh well...

Gene

"The value of an idea has nothing to do with the honesty of the man expressing it."
--Oscar Wilde