Is it true that marriage between relatives has many disadvantages?

Question:
May Allah reward you with good, and may He do you good. Shaykh Salih, some young people are affected by what they read about the disadvantages of marrying relatives. They list many things, including the transmission of diseases and the like, or more accurately, the inheritance of diseases. What is the ruling on this?

Answer:
There is absolutely no truth to this matter. The Prophet (peace and blessings be upon him) married his daughter Fatimah to her cousin 'Ali ibn Abi Talib. Relatives intermarried during the time of the Prophet (peace and blessings be upon him), and Muslims continue to intermarry among themselves, with families marrying one another. This claim that has appeared in recent times, made by some people or some doctors, has no basis and no truth. Therefore, one should not pay attention to it. May Allah reward you with good, and may He do you good.