In my language - Swedish - we use two genders called neutral and real. Like German and Latin languages (and unlike English) our genders have a large effect on the forms all nouns take: neutral has different indefinite articles than real has, the definite forms (a Scandinavian peculiarity) work differently depending on gender and so on.
However, we also have words that correspond directly to e.g. the English actress/actor (skådespelerska/skådespelare), and we have separate personal pronouns for he/she/it.
Still I think in general we consider our language to have two genders, since neutral and real is about how articles and rules apply to all nouns. A word like "actress" isn't seen as having a female form, rather it is a separate word in its own right, with the meaning "female actor".
You can look up "actress" in a dictionary, and it will have it's own entry, right? A word form dictated by gender would rather not have its own entry, but be understood as a different form of a base word which you could find in the dictionary.
Also I think, if a language has gender, and a word has a particular form in that gender, the general rule would be that that word should always, without exception, take that form for that gender. If a person said it otherwise, people would assume that that person didn't know the language properly. I.e., if someone called Elizabeth Taylor an "actor", it would just sound weird. (maybe that's the case? I'm not a native English-speaker)
Edit: forgot to add my conclusion - I'd say English has a single gender
9it used to be but isn't now. Most people nowadays would refer to any inanimate object as "it", commonly referred to as the neutral or neuter pronoun. So it's of neutral gender IMO, rather than having no gender at all, but your mileage may vary (which is why I didn't post this as an answer). – John Clifford – 2016-03-15T10:15:34.003
4"If we are talking about animate objects, like people and animals, defining a gender is easy in most cases." I don't think that's really the case for grammatical gender. For instance, should the grammatical gender of "cat" be male or female? There are both male and female (and neutered!) cats, after all. – Joshua Taylor – 2016-03-15T14:45:44.347
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Back in early medieval times when English was a language with declensions, grammatical gender was clearly marked. But English lost most of these declensions during the late medieval period and we have now only the vestiges of grammatical gender. http://projects.iq.harvard.edu/cb45/pages/grammatical-gender-replacement
– Tᴚoɯɐuo – 2016-03-15T17:52:06.0271languages tend to become simpler over time, for example in Persian there is no "he" and "she", I don't know if thats good or not! maybe sometimes the gender be removed from English too. – Ahmad – 2016-03-16T07:02:17.787
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Loosely related: http://english.stackexchange.com/questions/2484/are-there-sentences-in-languages-which-use-grammatical-gender-that-lose-meaning
– Steve Melnikoff – 2016-03-16T11:38:09.987