Yes, and child sexual abuse, sexual debut, etc. They are mostly based on questionnaires but children who debut early have universally shitty outcomes in mental health, teenage pregnancy, STDs, depression and suicide, and even total lifetime earnings. Do a pubmed search.
Hoards of scientific evidence decides if it’s harmful.
We have hoardes of data on the effects of child marraige?
Yes, and child sexual abuse, sexual debut, etc. They are mostly based on questionnaires but children who debut early have universally shitty outcomes in mental health, teenage pregnancy, STDs, depression and suicide, and even total lifetime earnings. Do a pubmed search.