Ilioi, E., Blake, L., Jadva, V., Roman, G., & Golombok, S. (2017), Journal of child psychology and psychiatry, 58(3), 315-324
There were no overall differences between disclosing families and either nondisclosing or natural conception families. However, within the disclosing families, more positive family relationships and higher levels of adolescent wellbeing were found for adolescents who had been told about their biological origins before age 7.
https://acamh.onlinelibrary.wiley.com/doi/full/10.1111/jcpp.12667