Question:
I read up about a surgery that deepens your voice, but does it work? Is it genetics? Can I deepen my voice though speech therapy?
Answer:
I have never heard of any such surgery so I cannot speak for it, but neither would I be likely to recommend it, even if I did know about it.
Some vocal traits are inherited while others are learned and can therefore be changed. I think that if you work with a good voice teacher or speech pathologist you will be able to have your best possible sound and avoid any invasive or potentially dangerous treatments.