What happened to Winston's family in chapters 1 through 3 of 1984?

The very fact that the text is not specific about
Winston's fate in this excellent novel gives testament to the way that Big Brother has
been able to warp and manipulate and ultimately control the memory of his citizens.
Winston is only left with fleeting memories, vague impressions and imprecise
recollections of his father, mother and baby sister that often surface in his
subconscious, as they do at the beginning of Chapter Three, when Winston wakes up from a
dream of his mother. Note how these memories are
presented:

He
must, he thought, have been ten or eleven years old when his mother had disappeared. She
was a tall, statuesque, rather silent woman with slow movements and magnificent fair
hair. His father he remembered more vaguely as dark and thin, dressed always in neat
dark clothes (Winston remembered especially the very thin soles of his father's shoes)
and wearing spectacles. The two of them must evidently have been swallowed up in one of
the first great purges of the
fifties.

Winston is only left
with fragments that he tries to piece together, however the one overwhelming certainty
that he has is that his family died so that he might live. Precisely how this happened
he is unsure of, but this is the message that comes through from his
subconscious.