do you agree that parental support in childhood is important to a person's mental and physical health in adulthood?

Yes. Our parents have a huge impact on our future selves. Studies show that if you grew up with parents that were abusive, did sexually inappropriate and did drugs, alcohol etc; you yourself are likely to do so. We need parents that can set an example for us children, we look up to our parents so its only natural that we would do the things they would.

Yes, and this is confirmed by studies.