Their parent(s) did cross a border illegally, however.
"sins" are a religious concept/term, not a legal one. We are discussing laws and consequences related to such.
Are people responsible for the good their parents have done? (To use your imprecise language.) This is a universe of duality/polarity.
Our laws treat children as property of their parents, in that perspective what their parents do implicates them as well.
Children inherit the genetics of their parents. Does this absolve the parents of any genetic illness or defects resulting from those genetics (DNA) passed on to their children?