Years ago there was a story arc about cleaning out a spare room as Janis’s sister and her kids were moving in due to marital issues. The problems were resolved though, and they never moved in. I think that was the only reference to any siblings.
It does take a specific personality and set of skills to build a house. Arlo, like many men, is limited to routine household chores. Managing the construction of a house requires many times greater order of magnitude of skills and time.
Years ago there was a story arc about cleaning out a spare room as Janis’s sister and her kids were moving in due to marital issues. The problems were resolved though, and they never moved in. I think that was the only reference to any siblings.