I shared my first wife with a college student - and she got pregnant. But, he was the same race we are (white). He had distinctly different features - and if the baby had been born, it might have raised some questions.
We got divorced. It wasn't
directly related to this incident - but, looking back, this incident was the beginning of the end.
My second wife was sterile ... and we only shared with BBC after that had been confirmed.
My third/current wife - would not consider a sharing situation - so there's no danger, there.