I've never thought I'd see such a topic on Hive but here it is. Interesting idea you're bringing here and I agree. Blockchain technology for medical purposes is an amazing idea.

Maybe the problem is: One donor, many children, with nobody knowing the full picture.

This can be a problem indeed and cause serious problems if not handled right. Imagine the genetic consequences.

I'll be checking back to see the comments later :) I'm not an expert in the matter, my knowledge is superficial in this regard, but not long ago I saw an ad about a documentary focusing on "black market sperm donations" and I wanted to watch it, but missed somehow. The ad said families opting for these services taking a huge risk.