For this you have to go to the following ->
system/function.php
the following is the codes of line you have to edit for extra gender ->
Line 919 you have to add the array so for instance array(1,2,3); you want to put 1,2,3,4 so add a comma after 3 and put 4.
then you want to scroll down to line 940 and add the language for the gender
so basic version for it when get unmodified files is
case 1:
return $lang[‘male’];
case 2:
return $lang[‘female’];
case 3:
return $lang[‘other’];
is how it is basic.
so add
case 4:
return $lang[‘(you chosen gender)’];
Now that you have done system/fuction.php
you will want to then go to system/language/your-language/language.php
scroll to line 21 you will fine the language pieces of code for the genders and just add your new gender underneath female.
Once you have added the gender just clear your cache. If you have redis cache active on your site make sure you clear your redis cache.
Clearing cache will just make it run smoother after the added code is update through the server.