I heard that some people, adoptees or kids without parents need medical attention and search out their parents for that info. Why do they?

If you're genetically predisposed to something like hereditary blindness, cervical/testicular cancer or sickle cell disease, getting help/treatment BEFORE the symptoms start is vital.

They would be better to go and see their doctor and get a health check and blood test

Bone marrow transplant may be necessary and a relative is usually the best match.

there are many illnesses that are genetic and knowing that is helpful.
ALSO, if the adoptee needs an organ donor, a relative is more likely a match than a stranger would be.

In my father's family there is the Alpha One Antitrypsin problem.. It is a liver deficiency that can lead to respiratory problems. When you have an infection, your white cells produce elastase to remove the infection. Then your liver produces Alpha One Antitrypsin to remove the excess elastase. If you have a deficiency in Alpha One Antitrypsin, not all the elastase is removed and it can do damage to the lung sacs. So someone who has the deficiency should be warned about not smoking and take care of themselves with any lung illness etc. Stay away from smokng.

If you are the one who was adopted, you should have a talk with your physician.

They might want to know if some diseases run in the family, such as heart disease.

I don’t know but I have a friend who was adopted and wanted to meet his biological mother and he was able to track her down through one of those agencies that does that. He went to Chicago and found her and knocked on her door and when she answered and he told her who he was she was really angry and said he had no right to do that. My friend is gay, an artist and pretty sensitive and I know the experience hurt him deeply. Probably more deeply than I’ll ever know. He probably wishes he had never done this.. I guess the biological mother just wasn’t strong enough to deal with the situation. Pretty sad.