I'm running Version 5, having done the incremental upgrades from Version 1. Strange things have happened in my games. The strangest was something that is NOT supposed to happen. In one family I had the parents have four children, get "old", and the wife died. The husband got a marraige proposal (surpise) which I accepted and when I checked the Family Tree I saw that he had disappeared, and was replaced with the new wife, who then appeared as the father/mother of the children! They now officially are the product of 2 moms!!!
I'll post the image in a follow-up email...got to figure out how to upload the image.