My clients, 2 sisters, had their names put on their parent's property (residential home) in 1991 via a quick claim initiated by their parents.  The house was purchased in 1962 by the parents.  Both parents are now deceased and the sisters sold the house in 2019.

Does the basis of the house go back to original cost?  Does it go back to house value in 1991? 

I prepared the return with basis as original cost, but thought it best to check.

Any comments/recommendations very much appreciated.