My dd (7) has been involved in 2 lots of research over the long term.
1st one started when I was pregnant and is looking into obesity in children. Involved blood tests plus weight etc and medical history of me and dh. Then dd when born was weighed, measured and had those pincer things for measuring fat. She goes back every year and has the same measurements taken.
The 2nd we've been doing since she was 15m. Its comparing over the long term children conceived naturally and those by IVF. They're very in depth assessments, looking at physical and mental development. Also asked loads of questions about me and dh, our backgrounds, health, brains...
We all like doing these things and wonder if anyone else is involved with similar things.