Question

Why the combination of dna copies from two pre existing individuals?

Answer 1

Because DNA replicates semiconservatively which means one of the strand of the DNA will be parental type and one strand will be newly synthesised

Answer 2

Hey!! Here Is Your Answer!!

"If each new generation is to be the combination of the DNA copies from two pre-existing individuals, then each new generation will end up having twice the amount of DNA that the previous generation had."
That is why the combination of DNA copies from the pre-existing individuals.

Hope It Helps You!!