It's just so creepy that Diana Rigg and Charles Grodin played brother and sister in the movie and both died of cancer

It's just such a cruel irony; because in real life cancer will usually run in families and if it happens to one sibling it can and usually does happen to the other; not to mention that they were within a year and a half of each other and their names together are the same names of British Royalty Princess Diana and Prince Charles [Prince Charles is still alive BTW] but on the other hand they were both over 80 years old when they died so you can't say that they were gone too soon.

Rest in peace to them both.