Ask a biologist

[nihilistcat]

Then that allows increased complexity of the DNA.  Are there any statistics on the frequency?

DNA breaks are a bad thing, it doesn't increase complexity except that obviously DNA repair mechanisms had to evolve to deal with strand breaks (but otherwise, strand breaks that are not repaired either lead to cell death, senescence, or even mutations that can lead to cancer). Single strand breaks occur thousands of time per day in all of our cells, whereas double strand breaks are rare (a few dozen at most in each replication cycle). 

What increases genetic variation is sexual reproduction, crossing-over (or recombination) during meiosis, etc. Here's a vid on meiosis:

https://www.youtube.com/watch?v=rqPMp0U0HOA