It's a complete invasion of privacy. The cause is obvious: Parents not acting like parents, not even having a close enough relationship to their children to know their mood.
More harm than good, but it's your choice as an adult to depress yourself and give away your intimate private data. Children are more vulnerable and don't always understand the cost.
Yeah so the NHS can then sell it to Google so it can profit from it. Fuck this. My privacy still matters to me!
"The data collected would be anonymous, the report says." - Might as well be my Great Granny saying this.