How are new people created from the DNA of an aged person. i.e. Why are we young?

Question

The question "why do we age" has been asked numerous times. But why are we young? The cells of the adult human being are an age (time>0), but how can old cells create new cells that are younger than themselves? I.e, how are young people made from the cells of old people? I realize that senescence, the act of a cell aging, has to do with the shortening of telomerase over time which puts a limit (the Hayflick limit) on the life of an autosomal cell. So in theory, because cells only make direct copies of themselves but the telomerase shortens with every division, each new daughter pair would be as old as the parent and would continue aging. But how come new people start senescence at time t=0?

Answer 1

This is because human germ cells, like eggs, are created before someone is even born. Regular cells that divide via mitosis do experience a gradual shortening of the telomeres over time, but human eggs are all formed in the developing fetus’ before birth via meiosis (two divisions only, not potentially infinite), and are (essentially) ready to go by birth. They do not replicate or divide further until ovulation/pregnancy. This is how they remain t=0.