How Can Sims Have Alien Babies in The Sims

A sim needs to be abducted by a UFO to get pregnant with alien baby.
If you type in the code:
boolprop testingCheastEnabled true you can press shift and click on a telescope and be abducted. You can also press shift and click on your sim and choose toombstone L and D and get pregant with Alien.
But remember to turn off code with fase instead of true when you're done, because it can cause problems.