After the first human sin children are born lacking the original grace God bestowed to the first image bearers (“Adam and Eve”). Therefore, the selfish mechanisms inherited through evolution become in the children’s hearts sinful propensities and, in this sense, @Klax is right when he claims:
In baptism we receive the grace of Jesus Christ, which is like a seed of righteousness.
If we don’t fight against the sinful propensities, then these “will grow up like thorns and chock the plant”; we will sin and develop “self-destructive habits”:
If we work to nurture this seed, at the end of our earthly life we will completely master the sinful propensities, and reach a “state of righteousness” even higher than that “Adam and Eve” had when they were created. Then we will really be “childlike before God” and “beloved children of God”, as you very well point out.
I would be thankful to know whether I am interpreting you correctly.