The Inteenimater is a pretty neato little hack (or set of hacks, I guess) that allows teens to do the WooHoo with each other, Y/Adults, and Elders (I think Elders, anyway, that's one I've never had the inclination to try). It allows teens to become pregnant, get married, move in, etc. and also does some other things, like add a 'biological clock' to every Sim, which says how long they have left to get crackin' on the baby making. Along with this, you get 'Birth Control', 'Risky WooHoo' (Meaning Sims have a chance to get knocked up even when not trying for baby), and Miscarriages (with custom memory). It was originally hosted on InSim, if I'm not mistaken, and then they branched off with their own site, then they decided to call it quits, and now it is hosted at Simbology. It really messes stuff up if you use the wrong version for your expansion packs, and because of this the creator was going to update it one last time for AL, but had a computer meltdown and decided not to start all over again (which is understandable, but disappointing none the less). I believe that others stepped in and updated it for AL, however, and for this I am very,
very excited. Inteen also has optional 'Flavor Paks' which can be used to add, well... flavor. Read about it
here.
If I'm not mistaken, Pescado very much dislikes Inteen, possibly because it doesn't work with a number of hacks. But, there's a handy little thing at MATY that lists what the FFS hacks do (
here), and the nice people that did those generally added a "DOES NOT WORK WITH INTEEN" bit, where applicable. The latest list there is for FT, but it is still quite helpful. Also, Inteen does not work with Squinge's
Pregnancy Wear Any Outfit, but some have sort of worked around that. There's a thread at Simbology on that subject - read more
here. In general, it's a pain in the ass, but IMO, well worth it.