Hardy-Weinberg principle

Question

The following paragraph on Wikipedia about the Hardy-Weinberg principle is bothering me.

It should be mentioned that the genotype frequencies after the first generation need not equal the genotype frequencies from the initial generation, e.g. f1(AA) ≠ f0(AA). However, the genotype frequencies for all future times will equal the Hardy–Weinberg frequencies, e.g. ft(AA) = f1(AA) for t > 1. This follows since the genotype frequencies of the next generation depend only on the allele frequencies of the current generation which, as calculated by equations (1) and (2), are preserved from the initial generation:

Why is it so that the genotype frequencies are dependant on the previous generation, but not in the case of the first as compared to the inital generation?

https://en.m.wikipedia.org/wiki/Hardy%E2%80%93Weinberg_principle#math_1

Answer 1

I can't think of a more succinct way to phrase it than the explanation in your post.

"...the genotype frequencies of the next generation depend only on the allele frequencies of the current generation..."

The genotype frequencies still do depend on the initial generation, they just depend on the allele frequencies of the previous generation, not the genotype frequencies. For example, an initial generation consisting of only (XX) and (xx) genotypes will produce F1 offspring with (XX), (Xx), and (xx) genotypes through random mating. Since the (Xx) genotype frequency was 0% in the initial generation, and >0% in the subsequent generations, it can't be equal that of the initial generation. But it will still be a function of the relative frequencies of the two alleles in the population, (X) and (x).