How can someone have more than one gender?

They just can. Gender is a spectrum

The HUMAN possibilities are:

1. Male - common

2. Female - common

3. Internally male, externally female

4. Internally female, externally male

5. Internally and externally NEITHER male nor female

6. Internally and externally BOTH male and female.

Note that in approximately 1 out of every 10,000 births the external visual cues as to sex are not sufficient to determine the TRUE sex of the infant at birth OR are incorrect.

Gender is what you identify as. You can be bigender and be both a man and woman, though sex is what's in your pants. So in essence the are more than two genders

gender is what is in your mind

people can be bi gender or gender f*cked which is changing who you are periodically from time to time day by day or even during one day

NOT inter-sexed

Gender is what you perceive yourself as.

Sex is what you have between your legs.

For someone who identidies as gender fluid, or bi gendered, they have more than one gender, even if what they have between their legs only corresponds with only one sex.

if you have a penis and a vagina its possible..