And the men said unto Lot, Hast thou here any besides? son in law, and thy sons, and thy daughters, and whatsoever thou hast in the city, bring them out of this place: for we will destroy this place, because the cry of them is waxen great before the face of the Lord; and the Lord hath sent us to destroy it. And Lot went out, and spake unto his sons in law, which married his daughters, and said, up, get you out of this place; for the Lord will destroy this city. But he seemed as one that mocked unto his sons in law.
(Genesis 19:12-14)
the angels mention sons-in-law, sons and daughters. i think they knew who they were talking about. Lot had 2 sons, 2 sons-in-law, and 4 daughters. but he didn't go to his sons ((why?)) he only went to his sons-in-law ((where 2 of his daughters were)). he balks at what the angels tell him all throughout this account, from beginning to end.
so Lot's sons were not warned, and they were among the men who sieged his house ((v.4 says all the men from every quarter set themselves around it)) - as were his sons-in-law. so they were left; the angels took everyone who was in the house with Lot by the hand. God knew this; guess why 2 angels were sent?
i think this is why Lot's wife looked back. for her sons. because she loved them.
this is the way i understand this, anyway. i am aware that it's not what is commonly taught.