Elder Son Rights

My father has built a small house in Bangalore in 1987. We are Hindus (Brahmins) We are two brothers and we were living in that house while we were growing. I got married (Love marriage and changed my religion to Christian) and moved out from that home and my brother was with my father and mother. Brother also got married and on dads property paper, he extended the house and is staying with parents. its been almost 18 years and he is settled in that home along with mother. I assume he must have made the property papers on his name while he is paying the loan for the extension of the house. My father is no more now and not sure if he has done any will. I am also divorced since 6 years and living alone. I am currently facing many issues and wanted to check my rights on my fathers property. Can I ask my brother on the equal rights? what will be my rights as a elder son on that property? My parents have been living with my brother and he has been taking care of them after I moved out. does this limit my rights? Please advice