The person I was responding to was talking about gender, but if you want to talk about biology then

https://en.wikipedia.org/wiki/Intersex#Prevalence

https://en.wikipedia.org/wiki/Klinefelter_syndrome

https://en.wikipedia.org/wiki/XXYY_syndrome

https://en.wikipedia.org/wiki/XXXY_syndrome

https://en.wikipedia.org/wiki/XXXYY_syndrome

https://en.wikipedia.org/wiki/XXXXY_syndrome

https://en.wikipedia.org/wiki/Trisomy_X

I assume you will be one of the advocates for my nobel prize

edit: I'm sorry you specifically mentioned gametes, we can talk about diploids and haploids if you wish and how our bodies are such complicated machines that any sort of error that can occur in our growth is guaranteed to at scale