Interesting to hear people say wild caught ones are docile but captive bred ones are snappy. I certainly have some lovely-natured ones I bred myself. A bit snappy for their first few months of life but darlings after that, and they're not young animals now.
The few wild caught Water Pythons I've been familiar with came into captivity snappy and stayed snappy, completely unworkable, all were NT animals. Have people found that friendly wild caught animals stay friendly in captivity, or they start out friendly then get pissed off after a while? What about wild caught hatchlings vs. wild caught adults? I would really love to hear about people's experience there.
Undoubtedly, friendly Water Pythons are more likely to have friendly babies, and snappy ones snappy babies (on average, in general, etc.). Behaviour in all species of animals has a strong genetic component. Obviously if you traumatise a snake and it gets snappy that's not going to be passed on to the babies, and if you socialise it to get used to people and handle better that won't either, but a snake predisposed to one extreme or the other will have a tendency to produce babies which are similar.
For the record, my adults are all darlings, they produce some babies which are darlings from the start, most hatch snappy and are lovely by about 3-6 months, and a few stay snappy. I obtained some as hatchlings and have kept some I've bred. The original animals came from Townsville blood.
If Water Pythons were all as good as the good ones I think they'd be extremely popular, highly sought after snakes. They look absolutely fantastic and the good natured ones are brilliant. They have a (partly deserved but misunderstood) bad reputation, but if you get a good one you'll be thrilled.