It depends on the high risks of the family. For instance, if there are two or more members having breast cancer from the same family, it is better to do genetic screening at the age of 20 itself. It is considered to be very important because we know that breast cancer is caused only by mutation with or without symptoms. In Madras or in India, the usual age group of breast cancer is anywhere between 40 – 60 but for familial cancer, it is definitely under 40. Early detection can prevent it from becoming worse. So, screening has to be started at the age of 20 and above.