Sisters on deed

[Donald Uher]

My two sisters and myself inherited our parents house on their death.  When parents purchased the house,  my two sisters names were included on the deed along with both parents names.   I assume my tax basis would be a small loss since it was sold slightly below fair market value (because we did not use a realtor, we gave buyer a little lower price).   But would my two sisters tax basis be the same as me?  Or would their tax basis be based on the original purchase price, and not the final fair market value since they both were listed on the deed?  House was in Missouri.  Should also note that the house was rented for one year (to same buyer) before the sale, which I assume made it into an investment property.