Rehat Maryada was never written by Guru Gobind Singh and the whole idea of "Rehat pyari mujhko sikh pyara nahi" is wrong as the oldest Rehat Maryada was also written down after Guruji's death, so how could Guru Gobind Singh Ji write such harsh words about sikhs for document which is non existent . The current Rehat was finalized in 1950.if u cut ur hair, then ur not a sikh. Read Reht namahs. How do call urself a sikh if u dnt even follow the basic principles.
Our history is not proper guide to historical facts as we all know that history is tampered with but we have Guru Granth Sahib Ji which is our great luck and accomplishment of sikhs as it was never allowed to be tempered by anyone. For our moral guidance we should look towards our eternal Guru and not some fudged historical documents and all our current problems will disappear.
Their is no specific instruction given in Guru Granth Sahib with regards to keeping long hair, on the contrary there is one shabad of Bhagat Kabir which states that you will not find God by shaving your head nor by growing long hair.
We should all try to live our lives under the blessing and moral principals of Shri Guru Granth Shahib and stop bickering our
chidlren for cutting their hair as it better for our children to be better human beings under the guidance of eternal Guru then for them to leave our religion all together.