Need Some Help

Ok I am working on an age restricted site, I dumped Joomla as it was going to just cost me more then I was able to support while getting it going. I am a bit more fluent with WordPress then Joomla, and love the functionality of s2member. My only problem is though the site will not be porno, I want and need age restriction to 21 and no matter where I look I can’t seem to find this to implement. I plan on buying the pro version in the very near future, though if I cannot implement age restriction in the registration field I just can’t.

I have to implement this to be able to verify to advertisers that I am age restricting content. A silly simple click through page is not enough to satisfy advertisers I am targeting, and I do not have the cash to outlay for a custom integration. Joomla handles it simply, WordPress an s2member seem to fail hard on it and I don’t understand why they do. Yes am a noob to all this, but it is a requirement I have to meet to get the capitol to take the site to a level I need.

If someone could just point me in the direction I will get it done, just lost at this point and will not pay for an alternative till i know it integrates correctly. Too much hype and not enough results out there.

Eric