The incident came to light when neighbours spotted the bodies on Monday.
When police reached the house, after receiving the information, they found the room of the parents locked from outside.
"In the initial investigation, it looks like a case of suicide. Although the family has raised doubts on some people, no proof has been found yet. Besides a mark from the noose, no other injury marks can be seen on the bodies of both girls," Noida SP Arun Kumar Singh said.
The girls' parents have pointed fingers at a relative, Ravi, who had been living with them with his eloped partner for past few days. After family members of Ravi's partner took her back, he and his family had allegedly been accusing the parents of tipping them off.
The parents have also alleged that Ravi's family threatened to kill their daughters on Monday and also said Ravi has "stained the reputation" of their older daughter.
The bodies have been sent for autopsy. (ANI)