The claim is completely false and has no evidence to back it up. It was posted by an X user with no identifying information on their account, and with only two posts. The National Institute of Health (NIH) website defines the term "gender" as "Gender can be broadly defined as a multidimensional construct that encompasses gender identity and expression, as well as social and cultural expectations about status, characteristics, and behavior as they are associated with certain sex traits" and it refers to the term "sex" as "Sex is a multidimensional biological construct based on anatomy, physiology, genetics, and hormones. (These components are sometimes referred to together as “sex traits.”)" A common mistake that people make is not understanding the difference between these two terms. Gender is defined by social constructs, which in theory, means that there could be any possible amount of genders. Sex is defined by biology, and according to biology, there are more than just two sexes. The United Nations Human Rights website says, "Intersex people are born with sex characteristics (such as sexual anatomy, reproductive organs, hormonal patterns and/or chromosomal patterns) that do not fit typical binary notions of male or female bodies. Experts estimate that up to 1.7 percent of the population are born with intersex traits." According to this research, there are neither only 2 genders or sexes, but instead a wide range of traits that can define how a person chooses to identify themselves.
NIH article gender and sex:
https://orwh.od.nih.gov/sex-gender
UN definition of intersex:
https://www.ohchr.org/en/sexual-orientation-and-gender-identity/intersex-people#:~:text=Intersex%20people%20are%20born%20with,are%20born%20with%20intersex%20traits.