Sister in laws are evil

[Nemisis]

I told that to the wife and now she's looking at me funny all of the sudden 

Is it possibly an "oh crap! There onto us" reaction?

Yeah, because you're a woman, and as such you both are collaborators against men.  We know how it works.   

Just more support for my theory.

What's up with fathers being so worried about their daughters?  And mothers so worried about sons?  But when they're the same gender, they let 'em roam free (or freer than the other parent)?

I'm trying to figure this out, because I haven't been in a parent position (hopefully not for a long time).  Why are we less worried about children of your own gender?  And why are we worried about those of the opposite more?

I have one hypothesis, for the father daughter proctectivity.

If the dad was a dog as a young man, then he doesn't want another promiscuous male getting his hands on his daughter.  But then what about the mother and son protectivity?

 
-Penguin

I'd bet your right on the first part.

And as to why parents are less concerned about children of the same gender, I'd put money on it having something to do with the fact that they can relate to them.

[SmokinLoon]

My sis-in-law is evil, no doubt.

2 days before I got married I had to go to her apartment to haul some stuff to the church for the ceremony.  When I got there, she acted a bit funny and after a bit simply came out and said it: "I've always thought you were hot, but since my sis had you I couldnt touch you.  We'll here is my chance, lets you and I head to my bedroom and experience each other and it will be our secret."  She went on saying "I'm going to head to my room and if you follow great, we'll keep it our secret, if not you can walk right out that door and no one will ever know and everything will be cool.  You're call", she said with a sly smile.  Then she turned and walked away while unbuttoning her pants.  As I walked out the front door I heard this loud cheer and upon looking up I see the entire family of in-laws waiting for me out in the driveway.

The lesson of the story???  Always keep the condoms in your car.   

[Nemisis]

How the hell is that the moral? Sounds to me like the moral is check to ensure her house and yard are clear.