Personally, I would not want to find out my mother/father/sibling was not biologically related to me because of some medical test.

Plus keep in mind that the family medical history needs to match the individual or at least it does if you want accurate health care. At some point they should be told. Its best if it comes from the parents.

However, I’m not sure about children conceived using sperm banks etec. Some may be thrilled that their mothers wanted them enough to do that, but others may not welcome this kind of news.

The dicision to tell or not will have to depend a number of factors.