It is a myth and this is the same shaky reasoning I always hear from people who have been on the "other side" (hiring). I don't blame you for it, it is your job to compensate people as little as possible while extracting the most wealth from them. That said, there are a lot of people who fall for this "if you have a family (of 20 dependents) you totally make up what you lose in salary!" fable and that puts downward pressure on all our salaries.