As a native of this fair land, let me offer an unsolicited pointer. If you are going to incinerate your son-in-law, daughter, and their child, you need to come up with a more American-sounding reason. It's not that we're particularly unused to gruesome murders in this country, but saying that you killed someone because they "were the wrong caste" makes people uncomfortable and may make them think that you'll next start dancing about with a bone in your nose or eating kittens or some other strange foreign custom. To show that my heart's in the right place, here are some suggested reasons that have a more "Non-Imported" ring to them:
1) "He was a fan of (Pick One: Jeff Gordon/the White Sox/the 49ers)."
2) "I told him not to buy a Ford, but he wouldn't listen!"
3) "He served light beer with the Christmas turkey."
and, finally, if you just have to tell them the real reason, at least make it sound more American:
4) "He was lowdown, no-'count, white trash!"