You could look into joining a twin registry. Discordant-twin designs are fairly powerful, but still need _n_>50 or something like that to be worth doing. Plus if you keep your own novel set of data, people will be less interested in analyzing it compared to a twin registry using a familiar set of questionnaires/scales/measures. (One of the reasons you see so much from twin registries or the UK Biobank: consistent measurements.) It would’ve been best if you two had been enrolled as kids, but perhaps better late than never.
You could look into joining a twin registry. Discordant-twin designs are fairly powerful, but still need _n_>50 or something like that to be worth doing. Plus if you keep your own novel set of data, people will be less interested in analyzing it compared to a twin registry using a familiar set of questionnaires/scales/measures. (One of the reasons you see so much from twin registries or the UK Biobank: consistent measurements.) It would’ve been best if you two had been enrolled as kids, but perhaps better late than never.