Back to the Source

A friend of mine and his wife are in Israel on vacation with her family, so we went out to lunch today with them. Then we left the women to go shopping and we went to shoot pool. Somehow in the course of the conversation my friend pointed out something very interesting to me that I'd never heard. We take it as fact that Judaism follows the mother. But if you look in the Torah, all lineage is described paternally. So at which point did it switch. He said during Roman times they raped so many women it was impossible to know who the father was, so the Bet Din (Sanhedrin?) decided to establish Judaism maternally, since it is obvious who the mother is. If this is truly the whole source to this, it should flow that if it is known who the father is, and he is Jewish, then his child should be Jewish, regardless of the mother. At that time this may not have worked, since they might not have wanted to admit to being raped, plus it was impossible to actually know who the father was if she had been with both her husband and a Roman. Now we can usually assume we know who the father is, and if not there are tests that can be done to figure it out. So why dont we accept paternal Jews as Jews? Any thoughts?