In the latest edition of the Tomodachi Collection series, Tomodachi Collection: New Life, players have discovered the ability to make male Miis engage in activities that have, previously, only been available to pairs of opposing genders. These activities include going steady, bathing together, proposing marriage to one another, having a honeymoon, and raising children.
The method for doing so is fairly roundabout, though: players must transfer the Mii in question to the 3DS using the Mii transfer tool, and the process only works on male characters. Nintendo has confirmed that this is an unintentional glitch and has begun work on a patch, which will be available soon.
Tomodachi Collection is very much like a Nintendo-produced, portable analogue to The Sims, exclusive to Japan. It is understandable that, with their family-friendly image, Nintendo may not wish to touch on certain, controversial topics. Still, it seems likely that quite a few people will not be patching their copies of the game.
Source: My Nintendo News