> However are you arguing then that these children who happen to be born into poverty should then be left in it without government/societal help?

First of all, UBI should ideally be enough to eliminate poverty. Parents might have to make some sacrifices to take care of the children (forgoing personal luxuries or taking a low wage job). Once the child is of age, they would receive their own basic income so there wouldn't necessarily be a cycle of poverty.

Moreover, we should incentivize child transfers by subsidizing adoption.

I think the UBI should cover the majority of families but there are still going to be irresponsible people out there. You're definitely right that the children should get out of poverty once they are old enough to receive their own UBI but I think there should still be some sort of program in place to protect the children of irresponsible parents throughout their childhood. I'm not sure of the best way to do that but overall their is probably a net benefit for society as poverty will inevitably lead to crime and physical/mental health issues.

> I think the UBI should cover the majority of families but there are still going to be irresponsible people out there.

If they're so irresponsible, why would giving them more money necessarily help the children to live a better quality of life?