Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
I'm a bit late to the party, but this resource is very helpful - stats.libretexts.org/Bookshelves/Probability_Theory/…. The key insight is that the probability of extinction $q$ for each generation is greater than the last, but less than 1, so $q_n \to q $ as $n \to \infty $.