If having children makes people less selfish, then by inference not having them leaves one as selfish and self-absorbed as ever?

There are many other ways of character-building and developing selflessness..

I'm not 'prickly' about this, as I'm quite happy with how my life has turned out; I've found travelling to less-prosperous countries and witnessing dire poverty and want has made me infinitely more aware of people's needs. One's own rather shallow self-interest tends to wane when confronted by extreme poverty and despair.
And I have encountered several 'mothers' over a long life in UK that hardly deserved the name. They certainly had little reason to be 'Proud'.
No, I think this idea smacks a bit of Smugness. Sorry!