In an open letter to the PM, which was released on social media sites Facebook and Twitter, Kumar said the comment was unbecoming of the office he holds.
"Your words have been taken as an insult by a large section of the people of the state and beyond. Most of us also feel that coming from you, the comment is rather unbecoming of the office you hold," he said.
"I have no doubt that this gesture of yours (withdrawing the DNA remark) would go a long way in assuaging the sentiments of people and would further enhance the respect people have for you," he said.
During a speech at a rally in Muzaffarpur on July 25, Modi remembered the way Kumar had invited him to dinner and later cancelled the invitation. The PM went on to add that Kumar had not only disrespected him but also a 'mahadalit' like former Chief Minister Jitan Ram Manjhi.
"Most of us feel these statements have gone beyond questioning my own descent. They have disrespected the lineage of our people and denigrated the great legacy of the state," the senior JD(U) leader said in the letter.
"This also gives credence to the feeling that perhaps you and your party hold a prejudice against the people of Bihar. I wonder how come the gravity of such statements repeatedly miss your alert conscience," he said.
"Earlier, your colleague and BJP leader Nitin Gadkari had said that casteism is in the DNA of Bihar. Interestingly, these are the same people who reposed their faith in you and contributed towards electing you to the highest office of the country with an overwhelming majority," he added.
