I have seen "your" used instead of "his"/"her"/"their" but this isn't what I see in Grammar books so I wonder if this use is common among English native speakers or if it sounds odd.
Q: "What does Dracula look like?"
A: "Your face is white, your ears are pointy, your teeth are big..." so, your instead of his
"My kids would have great butts if they took after your mother." Here, your instead of their
"They still need to find your pieces." Your instead of their
The Dracula example was said by a non-native speaker but the other two examples were taken from TV shows.
The your butts meaning their butts examoke was taken from a tv show called The challenge.
Your pieces meaning their pieces was on survivor Australia. I think I can get links. I'll re-watch it and check what I heard