Received: 10 September 2020
Accepted: 22 November 2021
First Online: 18 December 2021
: The parents were informed about the study in connection with their twins 9th and 15 the birthday. Participating in interviews, after being informed about the study, is regarded as verbal informed consent (age 9) and, at age 15 the parents agreed to participate via a web-questionnaire and digitally consented after being informed about the study. Both the CATSS-9 and 15 have ethical approval from the Swedish Ethical Review Authority (DNR: 2010/597–31/1; 2016/2135–31;2009/739–31-5) in which the procedures above were described and approved.
: Ethical approval from the Swedish Ethical Review Authority (DNR: 2010/597–31/1; 2016/2135–31;2009/739–31-5) included consent to publish.
: The authors have no competing interests.