“I appreciate your caring about me but these are my decisions alone and I alone have to live with the consequences “

“When you were my age were you making your own decisions?” (I’ve found this one to be particularly effective as the answer is normally that they were living a fully independent adult life at this stage)

It’s normally to do with a parent not realising their child is grown up. Being compassionate and patient but firm in not indulging it can help I’ve found.