Can you Atone for past mistakes?
The answer is no. All the patterns passed down to you from generation to generation can only be atoned for by moving forward, never backward. I mean, you can't do anything about your great-grandmother's patterns. That's her business. But you can atone for your children. By changing yourself, and keeping in mind that there's no better example than leading by example, your children will see a change in you and learn from this new "you" that you are now.
The Bible says it very directly. Even the third or fourth generation will pay for the mistakes of their ancestors. Change the word "pay" to "receive." It sounds different.
Remember, it's always from the here and now forward, never backward.