The Sims 3 on Wii: Why You Can't Have Children

Unfortunately, you cannot have kids in The Sims 3 for Wii.

While the game allows you to get married and even have a romantic relationship, the ability to have children and raise a family is not included in this version.

This is one of the limitations of the Wii version, as it's a scaled-down version of the game compared to the PC and console counterparts.