I'm well aware of this question, but the discussion came up on chat and I was encouraged to ask the question on meta.
Twins is a 1988 comedy featuring Arnold Schwarzenegger and Danny DeVito as genetically engineered twins. The fact that they're genetically engineered is used to explain the differences between Arnold and Danny, but the movie would've probably worked as well, if they'd been regular brothers. So it has one small SF element, but nothing it couldn't do without.
We actually had a question about the movie that was migrated to the movies SE as being off topic.
Junior is from 1994 and stars the same actors, as scientists who have developed a fertility drug, which they decide to test on Arnold's character, who becomes pregnant. This is a comedy as well, but this time it focuses on Arnold being pregnant, which is arguably SF.
As one answer to the question I mentioned reads:
Let's ask a few of these questions and see how they go.
So, how did this go?
Below you'll find two answers, one for Twins, one for Junior, to vote on to show whether you agree or disagree.