Anyone living/lived in a 2bdrm house with a biy and girl sharing a room?

What age would you want to separate them?

**backstory** we bought a 2bdrm house 10 years ago and it was a big surprise when we found out we were having boy/girl twins, who are now almost 3. My in laws (aka neighbors) think our 2bdrm house is ok for long term/retirement. Personally by 5 I would want them to have separate rooms.