But in all honesty the biggest weakness is one that you probably arent aware of and may realize later in life when you observe your choices from a time distance . Naivete is the biggest problem and we all share it to a degree. Obviously each one has weakness related to behavior ,addictive trends , lazyness etc that would not share with others but at least ought to share with ourselves and try to eliminate. Declaring those in an interview will prove lethal even if proper. If attaining the job leads to a better life for you and the company and a reduction of your weaknesses eventually(assuming you are a person that appreciates opportunities and respect those that provide them ) it may be proper not to disclose them. As long as you are true to yourself and an ethical person an interviewer should feel comfortable with the fact you are not going to answer the same way as you would to yourself that question. What is the purpose of the question really? You win it by being creative not honest.