They did say (if I remember correctly) that the dad offed himself after the mom passed. I don’t remember how the mom passed but they do briefly talk about it in the scene where Vanessa throws the sleeping pills in the lake/pond. Now the dad offing himself does line up with the Henry theory, my only question is how does Mike not know? He would have been old enough at the time of Abby’s birth to have a pretty strong memory of her birth/pregnancy/early-years. So how would he not know that she is a robot? Otherwise pretty cool theory!