Petunia married not Dursley but a university professor, and Harry ended up in a much more favorable environment. He had private tutors, discussions with his father, and most importantly — books, hundreds and thousands of science books and science fiction books. As a result, at age 11 Harry is familiar with quantum mechanics, probability theory, and other useful things. And most importantly — he is very rational, and that is more formidable than a radioactive spider bite.
Additional information:
1) The translation of the book and the audiobook are distributed under the Creative Commons Attribution-ShareAlike 4.0 International license
2) Chapters No. 64 and No. 99 are missing. They were not recorded. But that’s all right.
For example, Chapter No. 99 consists of only one sentence: Ten days later, the first dead unicorn was found in the Forbidden Forest.
That is the whole chapter.
As for Chapter No. 64, that chapter is quite specific. Perhaps that is why no one wished to record it.
3) The audiobook was taken from the page of the community "Harry Potter and the Methods of Rationality"