Should sperm banks limit the quantity of an individual’s donations?

So you donate sperm and produce 11 children for 11 different families.

Assuming these families aren’t aware that their child has all these siblings every where, what is to keep incest from occuring if one day these kids meet up and decide they have alot on common and well…you know what happens.

Is there something done to make sure that doesn’t happen? Be hell to marry someone and find out, 20 years and 3-4 kids later, he/she was your sibling.