Explanation:

When Guru Nanak was nine years old, his father was determined to make him wear a janeu (also known as yajñopavitam).
The Janeu is a thread (made from cotton, hempen or wool) that is worn by the hindu brahmins, kshatriyas and vaishyas of India. The thread of 'Janeo' suggests the development of a male, from a young boy to a man. The Janeu ceremony reinforces the superiority of a persons caste. This is form of racism in India has been used to control the hindu masses for centuries. Historically, hindus were indentified by the type of janeu they wore.

The string was to be draped over young Guru Nanak by Pandit Hardyal, the family's 'purohit' (brahmin priest).