Stupid question about fb ads

I put a fb ad in order to validate a business idea. Problem is that upon choosing my target group, I've noticed that men click on the ad far more than women do. But if the sample is biased (that is, if men on the target group chosen, are much more than women in the first place) how can one get safer estimation as to what gender is more interested on what we advertise? Are there any proxy ways to deduce what is the gender ration on certain populations (e.g. restaurant owners in specific geography)?