I wrote "Do you see her parents' house?" Duolingo suggested I had a typo and got rid of the apostrophe. As I sort of got the answer right it wouldn't let me report the answer for being incorrect. As demonstrated above the apostrophe is needed...
Unfortunately that seems to be a Duolingo bug. We have the apostrophes where they are supposed to be and you matched it correctly yet are reprimanded for a typo. We have reported this on several occasions and for now have to live with a "typo" non error