I saw this in a search for DNA today –Doctor Sues Fertility Clinic After Discovering He Has At Least 17 Unknown Children From Sperm He Donated Decades Ago: https://philadelphia.cbslocal.com/2019/10/03/doctor-sues-fertility-clinic-after-discovering-he-has-at-least-17-unknown-children-from-sperm-he-donated-decades-ago/.
Not sure how the lawsuit will turn out, but unless he has something in writing, it may be difficult for him to win. He may find he has a lot more than 17 children as a result of the donations once the dust settles.
This is becoming more common although sperm banks are now having problems getting donors after too many cases where remaining anonymous is no longer possible due to AncestryDNA and other DNA companies offering cheap DNA testing for genealogy purposes. A friend found a niece this way. His brother paid for medical school by selling to the local sperm bank. From my friend’s description, the brother made a lot of contributions to the bank. No telling how many other nieces and nephews my friend may uncover in the next few years. It probably won’t be as many half-siblings as this individual may have – Donor-Conceived Son Learns of 1,000 Siblings.
The flip side that some have pointed out is something along this line – Let Iceland Be Your Guide If You Plan On Getting Married and Having Children. In many cases, one or both parents are not the actual parents, but have not shared the knowledge with the child(ren). I recommend DNA testing if you plan on getting married and pregnancy is a possibility.