An utterly disgusting term
When they are young we push sex education and all kinds of millstone earning "knowledge" upon them and then when they are older we treat them like they are infants.
Ummmm, when my children reached adulthood, they did not stop being my children.
adult children as used in context meant ‘offspring’ not ‘incapable’. So adult children == adult offspring == you should have no problem with that concept.