Why 74%?

9 is in the heart family (3, 6, 9) and 1 is in the mind family (1, 5, 7). Mind with heart starts at 74. The nudge comes from the roots: 9 + 1 = 10, which leaves 1 when divided by 3, so the nudge is 0. 74 + 0 = 74.

Out of the 78 possible pairings, 30 score higher than this one. Rarity: 11.1% of birthdays from 1950 to 2009 give 9 and 11.1% give 1, so about 1 in 41 random pairs of birthdays land on exactly this pair.

The rule is our own design, not a numerologist's chart, and numerology is not a science.