Upcoming Torah Session

The Torah class I'm taking isn't till Tuesday evening, but I've been reading the Abraham story in preparation for it. That's such a complicated bit that we're going to spend two classes on it, but I noticed something for the first time this time through.
You might remember that tricky Abram/Abraham passes off his wife, Sarai/Sarah as his sister twice before fessing up to King Abimelech, and he never gets chewed out by God for anything he does, including that. But what I hadn't noticed before was that according to Abraham, Sarah is his sister--his half-sister. In that passage alone, there are several taboos that we take for granted now that were apparently no problem at all then. One was incest. (There's more incest in the story in the form of Lot's daughter's act of getting dad drunk and getting pregnant by him; if you ask me, they'd spent too much time in Sodom or Gomorrah!). The other was the mixing of meat and milk, when Abraham sacrafices a kid seethed in its mother's milk to God. This is specifically forbidden in the laws of Kashruth, but of course, Abraham isn't Jewish yet. There aren't any Jews yet.