The only connection a donor may have between their children is purely genetic. If the donor wants nothing more to do with the offspring, then they should have the choice of remaining anonymous. Presumably, the children produced are raised by people who applied for a donation, and though the application process should have been confirmed to be in a stable situation, capable of giving their child a proper upbringing. If the kid already has the care of parents, what else could it possibly need?
One thing that makes me extremely mad is how other people try to tell me that i have no right to know where I came from. It's supposedly all about how the donor feels. Very ridiculous. I have a say in this too. I'm just as human as everybody else. Therefore, I have feelings like everybody else. Why should there be laws keeping me from knowing who I am? Consider the morality of this from the offspring's perspective. Should sperm/egg donor anonymity be banned? ABSOLUTELY.