What is the reason for hereditary variation?

Hereditary variability makes the evolution of living organisms possible. Changes in genes are more likely to occur with sexual reproduction than with asexual. The fact is that asexual reproduction is inherently self-reproduction of the organism. The DNA of the parent and offspring is identical and very rarely mutations can occur in the offspring. During sexual reproduction, the offspring receives a unique DNA by mixing the genetic information of the parents. Mutations occur more frequently. Also, useful gadgets are transferred more often.