If that were the way marathons worked, I think the reaction of the audience to someone's struggle to finish the race would be different.
Not really. There are bad people who had wonderful parents and great people who had bad parents or no parents at all.
Child is separate new fresh human being, getting to human level from the level of vegetable over 18+-3 years.
The fact that it got some half of your genes doesn't make you special and if you don't let it die or get malnourished and give it chance at some positive human interaction and variety of fairly safe objects to tamper with it'll be fine and won't be much better off even if you tried you hardest.
Indeed, I would expect more support instead of less. "You should have known" may be accurate but it feels unhelpful.