I am not qualified to speak about this in any way other than being someone who has struggled with weight issues for a long time. From your post I would say that your over eating as a child was looking for comfort when your parents basically left you to it. So at a very young age you learnt to associate eating junk food with comfort and filling in the lonely and stressful times. I would also point out that the 70s were also the time when junk food really started to expand in the UK - especially the most addictive of them - high fat, high sugar. Please don't think that over consumption of these foods it's just down to your laziness or weakness it lack of self control. It isn't. When we eat junk food it gives our body a bit of a high, a rush of pleasure, gets the dopamine receptors fired up just as drugs, alcohol or nicotine does.
Putting the two together I'd say that hard wired into your brain is an almost automatic response to situations that you find stressful or lonely or unregulated or unplanned - you eat, usually something rubbish. It fills in the time, it feels good at that moment, it distracts you. At the same time it takes you out of the moment over and again until you find a whole afternoon has passed, you've fannied around and eaten rubbish, your dd had watched too much tv and eaten too many biscuits as well. But to your inner child that feels comforting - even though your grown up self can see what a boring, unhealthy, way it is to spend an afternoon - and what a negative lesson to teach your dd - hence the guilt.
The lessons were learn as children stick around forever and they are, in my experience, the default setting for how we are as adults. The ruts run very deep and changing those behaviours is truly one of the hardest thing s to do.
Labelling yourself as lazy doesn't help - if anything it's a get out clause! I didn't quite have your childhood but I recognise a lot of your patterns of behaviour in myself.
There are ways to change this, and it takes a while, but you can do it. For me recognising that I wasn't happy with my own behaviour was s big v step. So was deciding what to do instead. I find that having a plan for holidays etc helps.
Realising that my 'treats' were actually causing life to pass me by and were not positive choices, only patterns of behaviour that my brain find comforting because they were so familiar.
It's really hard when you realise that v your comforts are negative in your life. Finding new things to b replace them is probably the key
. Beating b yourself up out putting negative labels on it like weak or lazy doesn't help , if anything it pushes you back looking for more comfort.
Stopping now sorry for v the essay!