Per the answer to Are children adopted by Jews Jewish? a child that is adopted by Jewish parents when they reach adulthood (13/12) are given the choice of remaining Jewish. If I know of a child that ...
In a number of circumstances, the halachic status of מל ולא טבל ("circumcized but not immersed in a mikveh") takes on significance. For instance, regarding a nochri touching wine, the Shulchan Aruch ...