From an ageing reproductive stem cell's DNA to baby's “brand new” somatic cells' DNA

On the one hand, somatic cells's DNA age as life goes on, mitosis after mitosis, and that is reflected into reduced telomeres.

On the other hand, during life, reproductive stem cells must age too. However one half of the DNA of some random old reproductive stem cell is eventually transferred through reproduction, and the ageing cycle begins again, with new somatic cells with long telomeres.

What mechanisms can explain reproductive stem cells DNA do not age as somatic cells' DNA ? Or do we know how telomeres are growing back from old reproductive stem cells to gamete during meiosis ? Put another way, how is it possible that we are born with long telomeres ?

I am sorry for the formulation of my question. I think it is understandable but not really well written. However I don't know how to formulate it another way yet. Do not hesitate to reformulate it if you feel like it.