Ki Teitzei 5772

The Torah forbids a mamzer from converting to Judaism. The posuk (23:3) states that even the 10th generation can't. The Gra shows why the Torah emphasizes the 10th generation. The mamzer's son contains 1/2 of his father's blood. The grandson only contains 1/4 of his grandfather. The 10th generation turns out to be 1/1024 of the original mamzer. Based on a Yerushalmi in Terumos (10:5), 1/960 is enough to allow a forbidden object. In reality, the mamzer's descendant should be allowed to convert due to being more than 1/960. However, the Torah points out that he still cannot.