RJD chief Lalu Prasad declared on Wednesday that only a son can succeed his father in Indian culture, after party colleague Pappu Yadav claimed he was Lalu's real successor."Pappu Yadav is not my son. In Indian culture, only a son succeeds his father," the former Bihar chief minister told a public meeting at Sasaram in Rohtas district."After me, my son will succeed me in the RJD instead of Pappu Yadav," he said."If anyone has a problem with this idea, he or she is free to leave the party," Lalu Prasad added.It is the first time Lalu Prasad has strongly reacted to Rajesh Ranjan alias Pappu Yadav.Lalu Prasad has two sons - Tej Pratap Yadav and Tejasvi Yadav. Both are set to contest the Bihar assembly polls later this year.Even his elder daughter, Misa Bharti, who contested the 2014 Lok Sabha polls, will also be a candidate in the assembly election, RJD leaders here said.Lalu Prasad also taunted the media, saying it considered Pappu Yadav a criminal when he contested the Lok Sabha polls but he had suddenly "become a good man".Pappu Yadav said in February for the first time that he will succeed Lalu Prasad as the RJD chief.Pappu Yadav has already opposed Lalu Prasad's announcement of the likely merger of the six parties of the erstwhile Janata Parivar.Pappu Yadav was acquitted in 2013 by the Patna High Court in the murder of Communist Party of India-Marxist leader Ajit Sarkar in May 1998 due to lack of evidence.