So far i have had three spouses and two childeren suddenly die for no apparent reason, I tried leaving food in there inventory but got it back untouched on death. "hearts" were above 100 at time of death for all npc's also.

Wife and kids no longer seem to be dieing randomly. after a few experiments this seems to be happening mostly when you leave the area where your family are or come back from the nether after some time. no idea why this happens except the possibility that they may some how "suffocate" when the chunk they are in is unloaded.