Buy your own metaphor, a different seed planted and nurtured the same has a chance of success or failure. The fact that chances at all implies that the seed matters and not just the environment, otherwise any seed would be expected to have an identical outcome.
To speak plainly, children from the same parents with the same opportunities can and do have drastically different lives.
The crookedness the article speaks of is unpredictable and unique to every tree. Seeds planted in an orchard of the same soil do not produce identical trees