To identify genealogy you can not go for a DNA fingerprinting technology. It is against the Islamic Sharia Law and will cause disintegration of many families.

In this very connection, the Dean of the Faculty of Sharia and Islamic Studies at Kuwait University, Dr Mohammed Al-Tabtabaei said, “Islam does not allow the use of DNA fingerprinting to prove genealogy and no family can reject any of its members based on the results of such tests.”

He further added that Islam does not allow linking the crimes of fathers to sons as each of them is accountable for his own actions, “Although security departments can use DNA fingerprinting for issues related to national security, this technology should not be used as a tool to identify the family tree of anybody,” he said.

So you can see, in Islam, it is prohibited to know your family tree. To me, it sounds ridiculous. I feel, the result of DNA test would unearth the long hidden reality of their life. And as they are well aware of this fact that the truth of their life is not what they claim to be. Otherwise it would have been permissible.