Apparently you have ample proof from experience that you're not going to stop world evil by debating your in-laws into submission, so it's okay to choose not to try.

Your parents' views are, by current standards, out there. Getting in their faces about it would be needlessly disrespectful, but there's no reason for you to tiptoe through their delusional little terrarium as if you can't bend even one blade of grass.

I do crosswords when I have time to kill somewhere, and am 100 percent successful on filling in the spots I get stuck on - after I close up, do something else, and then go back to it.

If you take the time to listen to an upset child's story with empathy, and guide the child toward figuring out the root of the problem, then the result is often that the child not only calms down, but also in the future is less likely to get so upset.

Minimizing exposure to miserable people is nothing short of a life strategy.

Waiting for someone to propose to you only passes the "Really, it's tradition!" sniff test when both of you think it's the man's job to propose and both of you think that's awesome.

Plan your own vacations when you want to, and plan a suitable combined vacation with this other family when you want to. If they freak out at your planning your own vacations as you see fit, then let them. Bowing to unreasonable demands because someone will make you pay emotionally if you don't is not a healthy option.