I think that people have been getting mixed up with certain character's genders such as fiddler and keys and frankly Some people cant even decide, so they avoid mentioning their genders at all

The only characters whose genders aren't officially determined are Fiddler, Keys and Mr. Bigglesworth. Most people just choose what genders they think Fiddler and Keys are. I, for one, think they're female and male, respectively.

What Sleet said. The ones we don't know what gender they are isn't a big deal.

To clarify, of Fiddler and Keys, Rick has said that one is male and one is female, he just has not specified which. With the Biggles, any individual Bigglesworth may be male or female, but there are both male and female Bigglesworths, based on the accounts of the Bigglesworths themselves, at least.

It should be noted that the Mr. Bigglesworths are not entirely capable of distinguishing the males from the females either.

upon further inspection of some older strips I concur.