Prevent resgistration based on a selected profile field

Hello,

If, for example, I want to prevent women from registering on the site and anyone who selects 'female' as their gender, will be told 'this is a men-only website, you are not permitted to register'. How can I achieve it?

Or I have a tick-box question such as 'are you under 25 years old' if their answer is yes, the person is told 'you are not permitted to register on this site'. Answering 'no' permits registration. How can I achieve this?

Thank you