One would hope that you're wearing a sporran and that the sporran was weighting the material down as you sit...that helps.

...and if it would help to keep peace in the family, no one here is going to begrudge your wearing something like black boxer briefs to keep the strategic area obscured.

I honestly think that most of the bad reactions to kilties, such as the one that your mother in law is having, are based on the reactor having the idea that the kiltie is going regimental and thus is demonstrating a blatant disregard for the propriety of the reactor or anybody else in the tri-state area. Frankly, I really don't spend too much of my time worrying about the disposition of other peoples' nether regions, be they kilted or not, but apparently there are some people who do and we poor kilted folks must bear with their apprehension...hopefully with grace and good humor.

This is a perfect opportunity to try some behaviour modification, though. Express your genuine surprise that your mother in law has such feelings. Further express your genuine surprise that whoever ratted you out is such a total pervert that they were looking up your kilt. Say something like, "Well, this is an unfortunate turn of events, isn't it?" and then start finding excuses to not put in those appearances at your in-laws' place, kilt or no...let it be known that you are truly and deeply hurt that they would harbor such a low opinion of you and the national dress of your revered ancestors. Should they be coming over to your place, be kilted when they arrive but then excuse yourself and go change into trousers. Return to the company and don't say a word about it. It has now become "the elephant in the room". If anybody does bring it up, simply say, "I'm sorry, it's something that I would prefer not to discuss." and leave it at that. When mother in law is getting ready to leave, say your goodbyes before she exits and finish it with, "...well, excuse me, I have to go upstairs and change...bye." and go put your kilt back on.

Your situation is not too much different from one that I'm having with a very good friend (a woman) that I have. She doesn't like seeing me in the kilt. What the problem is, I'll never know. As I have told her when the question of any inappropriate parts of my anatomy becoming public domain arises, "I assure you that if I were to do a handstand right now, modesty would be preserved." She hosts lots of social events and actually asked me at one of them a while back, "How come you're not wearing your kilt?" to which I replied (very nicely), "Oh...I've decided that I'm only going to wear it for special occasions and to places where it's welcome." End of subject. It's a question of making it clear that I'm in control of the situation and making her think that her objections are silly and that I am the bigger person because I am letting the insult pass with grace. Bet your butt that when she comes over for my wife's birthday party next month I will be wearing a kilt, though.

Hope that my friend and your mother in law come around sometime but I think that it helps to let things sort of simmer for a while and let them realize that their objections are really trivial in the grand scheme of things.

Best

AA