Understanding Inclusivity and Reconciliation in Deuteronomy 23:8-9

I saw somewhere in Leviticus or Deuteronomy, something like, "Jews are not allowed to marry outside of their religion or they will be punished for 3 generations." I can't seem to be able to find this. Jews are not supposed to pollute their gene pool with Gentile blood. I have noticed that men that I have dated are from a Jew-Gentile Union are all Bi-polar. And women who are Bi-polar are from 2nd generation Jew Gentile marriages. I have a difficult time acquiring information regarding the 3rd generation. I suspect that the ancient holy men may have been aware of this phenomenon. Can you tell me the number of the scripture? Are you aware of this phenomenon? Thank you for your support.

Thank you for your question

I assume you are referring to this verse from Deuteronomy 23:8-9.

(8) "You shall not abhor an Edomite, for he is your brother; you shall not abhor an Egyptian, because you were a stranger in his land. (9) Children born to them in the third generation may enter the assembly of the LORD."

The instruction regarding the Egyptians, "You shall not abhor an Egyptian, because you were a stranger in his land," calls us to remember our shared humanity and the kindnesses that exist even in complex relationships. Though the Israelites were enslaved by the Egyptians, they also lived as sojourners in their land. the third generation if they convert can marry into the Jewish nation. This teaches us to acknowledge the complexity of human relationships and to find space for gratitude, even when reflecting on difficult periods of our history.

Wishing you much success.

 Deuteronomy 23:8-9.